Just a Test

I just learned something about Mathematica which could make doing things on this sometimes very math – heavy page a little easier. I can save formulae from my mathematica notebook as LaTeX strings as described by mdawaffe here  and in a wordpress.com faq entry here.

That works.

Turns out mathematica produces somewhat sloppy latex that often breaks the parser. It omitted the curly brackets around the \to block and adds supernumerary spaces. The mathematica latex export is just broken enough to force me to hand code everything! Wonderful… Still it gives a starting point and it might be easier than saving uploading and linking to image files for every formula. Maybe.

Grumpily,

The Astrographer

Astrographer’s Notebook – Introduction

I have an enormous collection of worldbuilding notes strewn across my desk, a dozen three-ring binders, a similar number of nice colored folders, and piled up in my book cases. These vary considerably in nature. Some are fairly extensive and occasionally comprehensible notes I took while reading various books and articles on physics, geology, astronomy, cartography, anthropology, history or whatever. Some are quick descriptions for what I thought would be interesting alien life forms. Some are quicky ideas for worlds or stories.

They are all taking up a great deal of space in my home. Space my wife and children would like to see a bit less cluttered. I love my family very much, but I’ve managed to keep my mess somewhat in hand, so that isn’t a horribly overriding priority. More importantly, in spite of all my efforts at logical organization, this is a hugenormous pile of stuff and it’s very difficult to find any specific items I’m looking for. This has lead to confusion, delay and duplication of effort. I have at least three copies of the sheet with formulae for relativistic accelerated motion. Assuming I wanted to do really hard SF and calculate the travel time for a laser-sail starship accelerating halfway to Alpha Centauri at a constant 0.01 gee and decelerating the other half at the same rate, I could figure out the time taken, both for the travelers and back home. That’s assuming I could actually find the sheets that contain the information. I used to have three copies, one sheet of which also had some biochemistry notes and something about matrilineal kinship, but finding it pretty much required me to look through all of my binders on physics and astronomy to find them. Assuming I didn’t have it filed under anthropology or chemistry ’cause of other stuff on the sheet.

I really need to get these things up on the computer, where I can look them up based on a variety of potential tags or categories. Probably my best move would be to create a wiki or three. At the top level of a categorical hierarchy, I would want to separate my notes based upon whether they were actual working descriptions of my conworlds as they exist. That is to say, I need to keep track of what I have already done on my existing conworlds. Another top level category would be actual real-world information I have gathered, whether the area of the Caspian Sea, a formula for the mass-luminosity relationship of main-sequence stars or James Kasting’s 1992 paper describing an equilibrium mechanism that might determine the depth of the Earth’s oceans. That last one is pretty cool, actually, I have a copy around here somewhere… The last important top-level category would be flights of the imagination, cool ideas I’d like to make something out of. On lower levels, I might have categories for religions, corporations or political affiliations within my conworlds, or physical laws differing from those we know in our own world, such as a description of FTL travel.

The important part of this isn’t in these categories, though. I have my notes all filed away in categories of one sort or another already. As blog posts, I could hunt information down using a variety of tags, both to narrow searches and to handle information that might well fit into more than one category of interest.

It gets even better with a wiki. I can search by title or tags. I can drill down through categories with individual notes possibly tied to multiple categories.

What I’m looking for, here, is a way to make my worldbuilding and ultimately my gaming or writing efforts more productive by making the information and ideas more readily accessible. This is largely for my own purposes, so bear with me, but I hope that it might prove of use or at least interest to my readers. If nothing else, assuming these efforts bear fruit, watching the process of my thoughts might prove helpful or amusing. If only in the way that watching the Three Stooges stage pratfalls is amusing.

Hopefully, this won’t be the whole of my efforts in the near future, but it’s a bit of added stuff to look over and laugh at. I’m still trying to find a way with this blog to try to make it something more than a vain exercise in… um… vanity. We’ll see how that comes out!

Thanks.

The Astrographer

Linkfest – Terrain Edition

The Synthesis and Rendering of Eroded Fractal Terrains(1989) - The classic by Musgrave, Kolb and Mace. This was a real find. While I’ve kind of given up on using procedural methods to generate global terrains, I still use procedurals quite a bit to detail the terrains I create. Often with a great deal of difficulty. While this paper is more than old enough to legally drink booze and graduate from the university, there is still a lot of meat in this paper. The description of their hydraulic erosion model should be of help if I ever go back and fix the precipiton node in planetGenesis. An interesting touch with the Musgrave et al version of precipiton erosion is that it accumulates water into little lakes over successive iterations, promoting flow even over surfaces with troublesome basins. I need to remember that bit, although I’d probably try to work in several non-erosive iterations to give pits a chance to fill before beginning actual erosion.

note: The Holder exponent, H, that he refers to is also called the Hurst exponent in other papers. H is often used in fractal algorithms in place of persistence. The Hurst exponent describes a relation between lacunarity and persistence, such that:

persistence = lacunarity^H, and

H = log(persistence) / log(lacunarity).

An Erosion Model Based on Velocity Fields for the Visual Simulation of Mountain Scenery(Chiba, Muraoka and Fujita, 1998) – More sophisticated erosion algorithms. This one seems like it could be applied equally well to a precipiton or an accumulated-flow model. I think working with accelerations due to slope rather than assuming steady-state flow velocities for given slopes increases realism. I’m not sure I understand the meaningful physical reality of the surface impact energy element, but it does add interest and another layer of customizability to the erosion process.

River Networks for Instant Procedural Planets(Derzapf, Ganster, Guthe and Klein, 2011) – This is an interesting completely procedural method for, as the name implies, generating planets as meshes. My interest of late has been the manual creation of planets as raster grids(heightfields, temperature grids, etc.), but I’d love to see an implementation of this one. I’d be interested in adapting this things algorithms for river network generation to grids. Particularly interesting is it’s formula for water and ground elevation along rivers.

The reason this method is constrained to meshes is mentioned in the article.

We use a mesh data structure because the algorithm of Kelley et al. requires labeled edges. While it would be possi- ble to store the planet in a displacement map wrapped around a sphere, only eight directions are possible for transporting water between neighboring cells, and a solution would be needed that can exceed these 8 directions when zooming in. Otherwise, parallel rivers would emerge. The mesh data structure supports two atomic operations – edge split and vertex collapse – that are used to manage the level of de- tail. Edge split operations can be applied to increase the level of detail locally when the user comes closer to parts of the terrain. The reverse operation, vertex collapse, restores the representation at the lower level of detail.

Perhaps this could be adapted to a mesh by use of something like the Tarboton d-inf flow-accumulation algorithm?

A screenshot of a program based on Doran and Parberry(2010). Note the large number of somewhat intuitive parameters controlling the generation process.

Controlled Procedural Terrain Generation Using Software Agents(Doran and Parberry, 2010) – This algorithm is another altogether procedural methodology(although with a lot of somewhat understandable parameters controlling the generation of terrains). The paper has lots of helpful pseudocode to clarify the various procedures.

It would be fun to play with the Mapgen3 program shown to the left. It doesn’t appear to be publicly available as yet, though. As with most pure procedural methods, terrain-building is more a matter of exploration(altering parameter and seed values and re-generating) than design. Though not a design-based method, the generously provided pseudocode makes it seem like a good program to try to implement. Probably, it would be better if I could find an existing implementation by someone with less meagre programming skills than my own…

RiverLand: An Efficient Procedural Modeling System for Creating Realistic-Looking

Teoh(2009)

Terrains(Teoh, 2009) – This one has the most user controllability of any of these. The user has the option to input the desired shore and ridge lines. A river network and a set of elevations are generated based on that information.

Teoh(2009)

For my purposes, this puppy may be the most useful methodology. I posted about this on the Middle Earth DEM. For their purposes they would need more control of river paths. I think, with a user-defined river network and skipping to the fifth step on creating an elevation map, this could be useful to them, too. Without pseudocode figuring out how to

Teoh(2009)

implement this algorithm would probably prove a formidable task for me, but looking at the results is pretty inspiring.

Realistically, I’m just really hoping an implementation of this is already available out there.

Belhadj(2005)

I just found Modeling Landscapes with Ridges and Rivers: bottom up approach(Belhadj, 2005). This one

Belhadj(2005)

has pretty good looking results, though I don’t find them quite as attractive as the ones RiverLand produces. The paper contains several pseudocode listings that might be of help in implementation.

When you’re as skilled a programmer as I am, you aim at the lowest point consistent with your goals. Honestly, if I could get something to generate a terrain that looks like the image to the left, I’d be very satisfied.

Finally, here are some additional related articles that I think may be of use but have yet to examine closely.

River and Coastal Action in Automatic Terrain Generation(Teoh, 2008) – At first sight,

Teoh(2008): Tropical karst, FTW.

this one looks complicated, but with a lot of real potential. It has several different profiles and growth patterns of mountain ranges, hills, deltas, beaches, headlands and meandering rivers. Like RiverLand, this one, called WaterWorld, produces some very attractive landscapes.

A nice attribute of WaterWorld is the

Teoh(2008): Nice coastal erosion.

|       wonderful coastal erosion effects. WaterWorld can also vary the placement of rivers based on a constant prevailing wind and existing topography, thus making wind shadow desert and wet coastal mountains. Sweet. I wonder if WaterWorld’s water model could be adapted to erosion. Maybe precipitons could be dropped at higher density on windward mountain slopes and lower density downwind of mountains?

There’s a lot here that could be of use to a skilled programmer creating a terrain-generating app. Much as I like this stuff, I think I’ll aim lower.

The Design Cycle

This is a subject I’ve spoken of a few times in the past, but I think it needs to be looked at with an eye to why we are doing what we do in the design cycle.

So we can start either from the top down or from the bottom up. In the top down, we have a real idea of what kind of world we want, maybe some of the cultures, we may in fact have a particular story we want to tell. So we work on building the underlying details to support that story. On the other hand, if the story is about a ship that has just found a planet orbiting at some random point within the habitable zone of a particular star, we might want to build up from the more basic astronomical stats and flesh-in the planet its life forms and cultures and see what stories that fleshing-in might provide us with. Or maybe we just want to experiment; play with what effects more extreme astronomical conditions might have on life and anthropology(or whatever the xenological equivalent of that might be).

In any case, it’s important to remember that this is a cycle, or more likely an oscillation.

We might start a bottom-up procedure only to find that our astronomical conditions were too extreme. Perhaps at some stage in the process it turned out to be implausible that you might have a sufficiently complex culture, or life… or even a planet. You’ll need to backtrack a bit to try to make the situation more believable. Or maybe a story suggested itself to you as you were building the world and now your backtracking to fit the story.

We might start a top-down procedure. We have some sort of a story and we want to fit the world to it. As we build downward, cultures and life-forms and geography are built to support the story. But perhaps they also suggest additions to the story. This may require changes to propagate back up through the overlying strata of life and history and plot. Or maybe you just change the story a bit and propagate changes down to fit.

At every stage, whether you’re building upward or downward, there are spreading forks of possibility. You only need to use your imagination to grasp them.

No matter how technical you want to be with your world-building, and I’m still gunning to be very technical, indeed, it is important to keep your imagination ever open. You need not only to follow the technical steps like an automaton, but be ever ready to see and follow the roads that those steps open to you.

This has been my failure of late. I have been focussing too tightly on the rote technical steps and failing to follow the flights of fancy, the new vistas opened to me by an entire world with which I can do as I like. This has not only bored me but it has stifled my creativity, made it harder to write and at the same time harder to read.

Whatever you start with, be it the basis of a story or just an astronomical caprice you want to follow, remember that start is not sacred. Great artists paint over their mistakes. If you feel that the development of your world has made your original story idea implausible(while providing more interesting story ideas), change the story. If you can’t fit the world to your story, and the world doesn’t provide comparably interesting ideas change the world.

If the world and the story both hold your interest, fork the project. Build a new world that will better support the story and save the world you’ve been working on for another story, one built off of that world. Or reverse that order. Whatever. The important thing to the design cycle is an eagerness to follow your imagination, and a willingness to go back and change things when they begin to constrict the story.

I hope that I was of help,

The Astrographer

2011 in review

The WordPress.com stats helper monkeys prepared a 2011 annual report for this blog.

Here’s an excerpt:

A San Francisco cable car holds 60 people. This blog was viewed about 2,600 times in 2011. If it were a cable car, it would take about 43 trips to carry that many people.

Click here to see the complete report.

Happy Birthday!

Yesterday was my birthday, tomorrow is New Year’s Eve. So, as a birthday gift, I’m going to give myself a better blog. Or try to. As a New Year’s resolution, “I’m going to write better blogs and post them more reliably.”

My wife has told me that my posts have been getting too wordy of late. She says that may be losing me some of my readership.

I’d like to avoid boring my readers and potential readers to tears, so I will try to reduce my wordiness a bit in the future. This imposes a bit of a complication for me. A lot of what I am playing with here is still a bit hazy to me in places, which makes it hard to describe things succinctly. Some of what I’m trying to talk about is inherently complicated and I’m oversimplifying as it is. To some degree, I feel a touch of complexity adds interest. These are supposed to be worlds after all.

In any case, I’ll try to intersperse the occasionally light and airy short piece in with the ponderous technical slogs you’ve come to expect from me.

That’s not to say I intend to reduce the level of technical complexity of my subject matter. To the contrary, looking back over my last few posts, I really haven’t been adding enough to what I have already said. Instead of going over every boring detail, I’ll try to cut to the chase. By trimming out the blow-by-blow tutorial-style procedures I hope not only to get more quickly to the interesting bits but also to speed my writing which has been scarily slow of late.

Clearly my workflow on Yaccatrice has bogged down in a terrible way. I’ve spent so much time trying to document the minutiae of dealing with numbers and mapping tools that I’ve kind of lost track of the story of this world. I am, therefore going to put the workflow of Yaccatrice on hiatus for awhile. I will post more of my results as I go along, especially as it gets interesting. If you’re just dying to see how I created my maps then I already have plenty of posts on building terrains.

I’m still kind of trying to get this site back up and running. I’m hoping after a few false starts I am finally going to get this thing running sustainably.

That’s one of my goals for 2012, anyway. To accomplish that goal, I really need to put more thought into just what I want this blog to do.

For everyone who has supported me on this blog for the last year and a half or for whatever part of that time: thank you for bearing with me. For those of you with an interest in world-building who just stumbled upon this site, hang out a bit… It’s going to get better.

Developing a Workflow – Part V A: Terrain Building(finding the seas)

So now we are on to Part V in the outline I’d given at the start of this little series. Although in the outline this stage is referred to as, “mapping,” I think, “terrain building,” is more accurate. The opportunities for cartography will continue. In this stage we are trying to create the baseline terrain which later maps will be intended to represent. “Terrain,” in this case refers not only to the elevations of the land and the locations of rivers, shorelines and the like, but also, in some generalized sense to the state of the local vegetation and ground cover. At this stage it would be good to have a better developed climate model for the world, but my climate model is still a stub at best(at least for a planet like Yaccatrice, with no axial tilt). Thus, I’ll need to at least make some kinda educated guesses about the climate of Yaccatrice.

Fig. 1: This is the initial sea mask. Seas are represented in white on a black background of land. Note how evenly distributed the seas are here.

I’m going to start stupid here. Initially, I just want to figure out shorelines and build up from there. I used a spherical perlin-based noise generator to create some nice shapes. Thing about perlin, or most any noise generator really, is that it’s very spatially homogeneous. Basically, the sea and land is distributed too evenly across the map. I have been working on some promising ideas for generating good, somewhat heterogeneous or clustered land/sea maps automagically, but for now I’ll try something with a bit more human agency. I used planetGenesis to generate an 8192×4096 mask image with what I found to be pleasant waterbody shapes and size variation. The one shown in figure one is reduced and saved in JPEG, ’cause 8k is just ridiculous for the internet. I just like to at least have a better suggestion of where smaller islands will be and what kind of shape they will have. Sadly, when it comes to later stages 32-bit Wilbur can’t really handle 8k images on my computer(it’s slow enough on 4k, but at least it doesn’t crash at the slightest instigation…). The next thing I did was to select each sea individually and put it on it’s own layer above a solid black layer. On the initial image(which was the background layer in my file), I used the lasso tool to select the area around a sea I desired. This could contain one or more individual lakes closely clustered. Once I had the broad area of the sea selected I went to the magic wand tool(best named tool in the box, I use it for damn near everything). With a tolerance of 128, contiguous unchecked, and an application mode of, “intersect with selection,” I clicked well inside a white area(due to antialiasing, the thin grey areas around the edges of the white areas could result in bad selections, but the problem should be really obvious if that happens). That will select all of the distinct white regions within the area delineated by the lasso selection. Very nice that. As it turned out I moved my seas around a bit, mostly just east and west to avoid distortion, but sometimes also a bit north and south.

Since I did move some of the seas north and south, I decided I needed to verify the relative area of the various seas. When it comes right down to it I’m willing to give up on my original size statement(Mediterranean-sized for the largest, down to, I think, Lake Erie for the smallest), but I didn’t want to find out later that the Seppama(seventh) Sea was actually larger than the Tersha(third) Sea. To do this, I selected the entire canvas(Select All – cmd/ctrl+A), used Copy Merged(shift+cmd/ctrl+C) with all of the sea layers and the underlying black layer(and nothing else) visible and pasted(cmd/ctrl+V) the result above everything. I used the Flying Pear Flexify 2 filter on this with an input projection of equirectangular and an output projection of cylindrical equal area. Since this new map is equal area, the pixel counts given by histogram should be proportional to the actual spherical surface represented by these areas on the map. Using this, I can approximate the actual surface area of each of the seas by taking note that the number of pixels in my image(8,192 x 4,096 or 33,554,432 pixels) represents the total surface area of the planet(4πr²or, for Yaccatrice, 389,310,635 square kilometers and some change) so each pixel represents about 11.6 square kilometers, a square area about 3,406 meters on a side. So the Paima Sea has an area of about 2,644,330 square kilometers, the Segonna Sea has an area of about 1,195,960 square kilometers, the Tersha Sea has an area of about  827,670 square kilometers, the Karta Sea has an area of about 710,630 square

Fig. 2: This is the final sea mask after I had done some manipulation on it.

kilometers, the Kanta Sea has an area of about 309,710 square kilometers, the Sekta Sea has an area of about 129,000 square kilometers, and the Seppama Sea has an area of about 56,610 square kilometers. Since my quantum of measurement is approximately ten square kilometers, I’m rounding off those last two digits. I also know that the hydrosphere of Yaccatrice comes to about 1.51% of the surface of the planet. This is a desert planet.

Now that I know where the major features of my land surface are, the geographer in me

Fig. 3: This is my map with annotations. It may not look like much, but at this stage, the name of the game is terrain-building, not cartography. Have patience, Grasshopper!

can start making some inferences. First of all, let’s look at figure three, which puts some names on the landscape. This is, if nothing else, an aid to future communication.

I think having names actually on the land adds a lot to the feel of the world. Now I can start making final decisions about where things really lie on the land. Details, like where mountains are, or where does the rain fall are still pretty sketchy, but I know which seas are neighbors and I can make some halfway decent guesses about relative distances between places. This feels like a huge step. I think it is.

Now I’d like to think about how to make a sensible whole out of this pattern. First of all the dry areas are either going to be higher than the seas and draining into them, or the rates of evaporation are going to exceed the rates of precipitation in these areas. Also, how do I make some sort of geological sense out of this? Is plate tectonics likely to happen on a planet with so little water? I don’t know the answer, but I’ll assume yes to

Fig. 4: More information on the map of Yaccatrice. The Rainshadow Mountains are shown clearly, if diagrammatically (they might follow a more direct north-south trend, perhaps forming rift mountains between the continent to the east and the trenches in which the Tersha, Karta and Sekta Seas lie). The possible continents are delineated in green, although their shapes may also change somewhat.

keep things going. Otherwise, I’ll disappear into another research-fest for the next couple of weeks and never get anything posted. Given plate tectonics, I can assume that the sea regions are the low areas of this planet’s, “sea beds,” and that the water settles down into the subduction trenches. Some of those wastelands may be the tops of continental plates. These places would be dry, thin-aired places, probably cold, even at the equator. Orographic uplift of air masses moving up the continental slopes will cause moisture to precipitate out of the atmosphere, draining into the seas and rendering the continental surfaces high and dry. This is starting to make sense. Yaccatrice is starting to look like a really alien place.

Since I want a fairly considerable patch of desert between the Tersha and Segonna seas, I’ll add a high mountain range just to the southeast of the Tersha Sea. That’ll make the Segonna/Tersha route something of a hardship. I figure Tersha, Kanta and Sekta will be less significantly isolated, being separated only by steppelands and the occasional death valley.

Human inhabitants originally arrived at the Segonna Sea and gradually spread to the Karta Sea, then the Tersha Sea and on to the Kanta and Sekta Seas. Further expansion has been inhibited by the great distances to Seppama and Paima Seas, the hostility of the regions between these Seas, and the relatively primitive state of Yaccatrene technology.

At first sight, the best route for expansion from the populated Seas seems to be from the

Fig. 5: A globe view of the northern route, connecting the Sekta Sea to the Seppama Sea and thence onto the vast Paima Sea.

Sekta Sea to the Paima Sea via the smaller and less desirable Seppama Sea. The desert between the tiny Seas of Sekta and Seppama is still pretty huge and hostile, even if it is cooler and somewhat less malignant than the other routes. Also, the journey from Seppama to Paima would still be quite long and arduous.

For reasons I still haven’t figured out how to justify, the northern hemisphere is somewhat colder than the southern, which affords the possibility of an arctic ice cap not far north of Sekta and Seppama Seas. On the one hand, this provides travelers with a readily available source of water. On the other hand, this might restrict travel to lower latitudes, making the journey longer.

The, “second best,” route from the populated Seas is directly from Karta to Paima across the Great Parched Waste. This is a longer journey than the Sekta/Seppama route and crosses the hottest tropical belt of Yaccatrice. Anyone crossing this way would need to be

Fig. 6: The direct route across the Great Parched Waste. Only for the hardy... or the foolhardy.

hardy indeed and very well prepared. The one thing that can be said for this route as opposed to the northern route is that Warks don’t cope well with colder temperatures. Warks are a crucial beast of burden for any major dessert crossing on Yaccatrice.

The last and by far most difficult route, is westward, across the Wastes of Bleached Bones. Not only does this appear to be the longest of the three journeys, it crosses some of the roughest, driest and most hostile territory on Yaccatrice. Barring some sort of technological advance unknown to the peoples of the Five Known Seas it is highly unlikely for humans to have ever followed this route. Barring an indirect route, which would make the hazardous journey even longer than the direct route appears, travelers would have to cross some of the highest mountains on

Fig. 7: For many reasons, the Wastes of Bleached Bones are by far the hardest way to get to the unknown Seas. In the north, one can readily freeze to death. At the equator, one can die of the heat. In the mountains one can suffocate or freeze. And one can die of thirst anywhere in these wastes. Even pilgrims to the occasional settlement at the far eastern edge of the waste near the Seas routinely fail to reach their destinations alive.

Yaccatrice. There are only a few routes over these vast unnamed mountains that are low enough to allow unaided humans to breathe the air. The northern part of the Wastes of Bleached Bones may be a likely place for large continental glaciers to form. Now that I think of it, increased albedo due to the runaway glaciation of the northern Wastes of Bleached Bones may be a good reason to have the northern hemisphere be generally colder than the southern. Cool. I love it when a plan comes together!

On the other hand, I suspect the easternmost Wastes of Bleached Bones, at the crumbling feet of the continental slope, may be a good place for some of the more austere and isolationist monasteries to set up business over more reliable springs. Honestly, though I suspect monasteries and the refuges of hermits dot many of the deserts within a few hundred miles of the more verdant Sea regions, even the Brothers of Perpetual Solitude would probably find the average caravansary between the Segonna and Tersha Seas sufficiently isolated.

Although my original intention, to complete the full task of building the terrain of Yaccatrice, was not accomplished during the production of this post, I really feel this world has been fleshed out immensely over the last few days it took me to write this.

I must reiterate that I very much appreciate any comments and suggestions that you might have to add. The purpose of this blog, after all, is to build a community of world-builders. Thank you for your attention.

The Astrographer.

Updating the Look

I just updated to the 2011 layout(not bad for late december). I thought I’d check out the Ephemera sidebar. Can’t say as I’m fond of the default font. The layout options were a real improvement, but I could hardly read the text, so it’s back to 2010.

Developing a Workflow – Interlude: Biology

Looking over my planned workflow, I saw a major hole in the worldbuilding. Biology. I know I already handled biology in the very sketchy sense of saying that Terran and Yaccatrene organisms were capable of feeding on each other, but that really doesn’t give much one much of a feel of what it would be to stand near a Yaccatrene sea and see the trees, hear the calls of native animals, and smell the soft perfume of alien vegetation. Partially I tend to pass lightly over this because of a failure of imagination. Also, my artistic skills can’t support the needs of visualizing an alien world’s lifeforms. Since my mapping efforts are still going slowly, I figure I can make at least a survey of what others have done in this vein. So here goes.

First off, we have Life on the planet Furaha by Gert van Dijk. This and it’s associated blog are a joy not just for the extraordinary artwork, but for the technical thought that went into the organisms. Particularly appealing are his size comparison silhouettes often showing humans swatting off obnoxious swarms, trying to push large refractory animals from behind, being flung through the air by large refractory(and annoyed) animals or just swimming along. Some of the work he’s done on flying, walking, and swimming are really fascinating, informative and… detailed. I’d love to take a gander at some of Mr. van Dijk’s matlab scripts! His site is a gem, but it’s really worth reading his blog from start to… where ever he’s at right now.

Snaiad by Nemo Ramjet is another classic of alien biology. Sadly, his main site is long dead, but he still has a Deviant Art page. I kind of despise Deviant Art as a site, but some of the artists working on alien biology make it worth dealing with. His work is highly imaginative and clearly shows the power of consciously applied perversity. Excellent.

Another great artist on Deviant Art is Alex Ries, who goes by Abiogenisis. I’ve had Alien Parenthood as my desktop image for some time now, and his Birrin are a real study in the complexity, diversity and history of a genuinely believable alien race. Even his alien animals are quite interesting, strange and believable. Clearly, he has an interest in brachiators, but his animals have real variety, while feeling like they fit together as evolutionary relatives.

Through a link on the Furaha site, I found Evan Black’s Nereus. The animals of Nereus have a wonderful combination of exhilarating strangeness and comfortable familiarity. I’m looking forward to seeing more work on plants. As often seems to be the case, his blog on the development of Nereus is very instructive to anyone considering developing their own constructed ecologies. Other than, possibly, the history and cultures of a worlds intelligent denizens, this is clearly the longest and most involved process in world-building.

Since this was never intended to be a giant super-project, I’m not going to do more than give an overview of the problems of developing an ecosystem on Yaccatrice and the sources of extraordinary diversity and interest that could exist here given the peculiarities of this world.

As I’ve mentioned before, life on Yaccatrice arose independently in at least three separate seas and spread into an oddly woven ecosystem over all of the seven seas. Maybe I should say set of ecosystems. While all three of the independent roots of Yaccatrene biology have had the mobility to spread to all of the places on the planet where complex life could flourish many of those places are still more isolated from each other than any place on Earth has ever been. This means that each of the seven seas has its own very different set of life forms. Even some smaller geographical divisions have formed into strange little Australias of isolated evolution within some of the larger seas.

As to actual organisms, I don’t have a real good image of the life of Yaccatrice, but I do have some hazy little images and ideas in head that I will share.

The Kanta Sea Biotic Domain was the least significant of the three independent roots of life on Yaccatrice, but it provided some of the commonest small organisms on the planet and one of the odder ones. Before animal life crawled out of the waters of the Kanta Sea, the shores were already greenish-grey with a form of vascular fungoid producer that may have originated from one of the larger neighboring seas or may have been native. In any case, while the descendants of the vascular fungoid producer have been more or less successful on the shores of five of the other six seas, it has been eliminated from the Kanta Sea region by competition with an odd creature. They may have been outcompeted by one of the odd life forms that originated from the Kanta Sea. The herbabestiae is a group of at least partially photoautotrophic organisms evolved from an earlier heterotrophic ancestor.

A mass extinction event seems to have decimated all of biotic domains of Yaccatrice about three billion years ago. Besides greatly reducing the diversity of the other two biotic domains and possibly wiping out a fourth domain that might have originated in the Sepama Sea, the extinction event seems to have nearly destroyed all of the existing photoautotrophs native to the Kanta Sea. While this extinction probably took several millennia, dwindling populations at the bottom of the food chain began to exert ever increasing evolutionary pressure on the remaining species immediately. With the exception of a few scavengers and detritivores, Kantese animal life had been reduced to a few species of soft worm that had incorporated organisms analogous to chloroplasts or blue-green algae as symbionts. Although photosynthesis was merely a subsidiary process for these organisms, it gave a few of them the narrow edge they required to stave off starvation for several generations. As it turned out, though the earlier plant life began to recover, the proto-herbabestiae had already begun to fill in many of the more productive ecological niches and eventually the previously existing aquatic plant life was relegated to  marginal places in the ecosystem. Literally. With the exception of unicellular phytoplankton-analogues, true plants were limited to the shallowest waters near the shore. With their ability to maintain position where the sunlight is best, even against currents in deep water, the more efficient chlorophyll-analogue of their photosynthetic symbionts, and their ability to consume other plant and animal life, these proto-herbabestiae found themselves dominant over the vast majority over the Kanta Sea. By the time the first of these organisms had emerged from the seas evolution had already equipped them with the tools to completely outclass the rather primitive vascular pseudo-fungi they found on the shore.

Most of the existing native Kanta Sea fauna are now of the “phyla” carodurae, mollicutae, viridlimax, or herbabestiae. These are all derived from the basal herbabestiae with various adaptations. In the case of the carodurae and mollicutae the photosyntetic capability has almost completely atrophied away. The viridlimax still retains the limited photosynthesis of the aquatic ancestors of the proto-herbabestiae. Except for the juvenile traveling forms of some species, modern herbabestiae are all completely sessile.

Two other, even vaguer ideas I have had for native plant life are bulb-trees(arborampullae), and propeller seeds(seminarhoncus). The bulb trees are a little

My attempt at drawing a bulb-tree

unusual for being one of my rare visually-oriented ideas. Basically, the tree is a collection of fairly vertical trunks growing out of a large ellipsoidal bulb from which the roots grow down into the ground. The basal bulb-tree has no branches as such, its spread provided by the gravitational splay of its trunks and by the large leaves which I imagine would resemble palm fronds to some degree. Now that I have a picture of it, such as it is, it seems to broadly resemble bamboo. Perhaps there are cane and grass species derived from the bulb-tree base. I also imagine there would be a kind of mangrove bulb-tree, with its bulb held up above the water on high stilt-like roots and glands capable of rejecting salt from its absorbed water. Given the lack of seasons on Yaccatrice, mangroves should be able to grow along the shore in much cooler average temperatures than on Earth as freezing winters won’t be a hazard over a wide range of temperate climates. As you can see from the drawing, this blog needs a staff artist. Anybody want an unpaid job?

Propeller-seeds aren’t quite the same as the propeller seeds of maple trees. One species of seminarhoncus on Yaccatrice uses them in a semi-carnivorous life-cycle. LIke all seminarhoncus its seed bases build up a great deal of torsion as they dry. In this case the seeds burst preferentially when a shadow falls across the tree. This releases dozens of 100 gram hard spinning blades, each carrying a seed. Left to themselves, these seeds can fly up to 50 meters across flat regions. The seeds are capable of embedding themselves into animals within about 10 meters. When this happens, the seeds are capable of much wider dispersal. The shell and wings of the seed act as a slow poison, typically killing animals of 5-20 kg in anywhere from an hour to a day or so. Smaller animals are typically killed immediately by the impact and larger animals usually survive the effects. Besides dispersing seeds over a wider region, the decomposing corpse also provides the newly germinated plant with a readily available source of nitrogen-rich soil.

A long time ago, I saw a fantasy painting of a caravan of giant elephant-like creatures with what amounted to small castles on their backs. These behemoths were trudging through a deep rocky valley, surrounded by high, bleak, foreboding mountains. My attempt to find this image on the net has been a colossal fail of my google-fu. Bugger! Anyway, I’m wanting giant thick-skinned hexapedal monsters to carry travellers across vast stretches of desert between the various seas of Yaccatrice. For historical reasons of my own(which I may have mentioned before?), I am calling these leviathans of the dry wastes, “Warks.” If anybody can find the image and let me know where I can find it, they will be rewarded in the best manner I can afford. At present that means I will mention your name on this blog and direct all four of the other people that read it to check out your blog or website or whatever.

Latest news! In the process of putting together a blog on building the terrain of Yaccatrice, I have had some ideas that add a bit of flesh to the Warks.

Warks and Warkid Hexapods

The genus to which the Wark belongs, contains several species of animals well adapted for crossing desert expanses. The Wark is about twice the size of an African elephant, although after a long desert crossing with its water reserves depleted, it’s only about a third more massive than an elephant. In other words, they can store up about two-thirds the mass of an elephant in water and nutrients. Other warkid species range from the size of a small pony to a bit bigger than a Wark. Almost all warkids are able to store up proportionally similar water and nutrient reserves. All warkids have an excellent sense of smell, being able to sniff out desert springs from many miles away. Wild warkids have been found at all five of the known Seas and one can assume that they are also present at the Paima and Seppama Seas. Few warkid species subsist on desert land. Like Earthly penguins, the proto-wark and most present wild warkids simply found desert oases as an excellent refuge to raise their young, safe from the predators and other dangers of richer climes. In order to reach their mid-desert spawning grounds, these proto-warkids needed to cross wide expanses of often rugged arid desolation. They also needed a way to carry the food and water they gathered elsewhere to their young.

All warkids have large panniers that carry up to a third of the warkids total mass as a fat, protein and water-rich milky substance. As with mammals, they have teats along their sides that allow them to feed the fluid to their young. After giving birth, females leave the young to the males to feed and care for out at the oases, while they head to the more hospitable regions around the seas to feed and drink and refill their own panniers. Even with full panniers, the males and the calves they care for strip the oases of vegetation and drink down any of the available till only the thin trickle of water from the spring serves to keep the trampled and denuded mud slightly damp. The species of vegetation found at these oases are well adapted to recovering from this predation and, barring human interference, is usually verdant again by the next warkid mating cycle. Warkids are even capable of sucking the moisture out of mouthfuls of mud. Finally, the females return with full panniers. Both the adult males and the young are fed from the female’s panniers. The young at this point are large enough and well-developed enough to make the journey back to the nearest Sea. Humans find the milky fluid nutritious and reasonably palatable. Wark-milk is one of the assets that make Warks such valuable desert pack animals.

Besides the panniers, the warkids have other adaptations that suit them well to crossing hot dry deserts. During the hottest portions of the day, warks hibernate and reduce their respiration rate to an absolute minimum to retain water. They cover themselves with a large tail covered with loose shaggy strips of dead white skin held well above their bodies, maximizing air circulation and reflected radiant heat and minimizing conductive heat transfer between the surface exposed to the sun and their living tissues. They also hold themselves well above the ground on wide-splayed feet, giving them the ability to cross soft ground while allowing them to minimize the contact surface with firmer hot surfaces. During the day, warkids try to stop on harder ground where their feet don’t sink in. During the night when warkids spend most of their waking hours while in the desert, they can store up oxygen as a highly toxic and richly oxydized organic nitrate compound in a large back hump. Besides allowing them to reduce their breathing rate still further during the day(analogous to the crassulacean acid metabolism of some terrestrial xerophytes), this toxic compound also makes them unappetizing to most predators. Developing this nitrate layer is both a major reason allowing young warkids to make the journey back to the sea regions and also allowing them to be safe from predators when they get there.

Most of the hexapodal subphylum to which the warkids belong have kidneys that lead to urinary bladders and one or more excretory pores that allow urination. Warkids, while they retain a tiny urinary bladder don’t actually excrete urine directly, but inject it into their extra-long water-recovering large intestine to help lubricate the passage of their desiccated fecal matter, thus allowing them to increase the water-recovery efficiency both of their kidneys and of their digestive tract.

The long and convoluted nasal passages of the warkid have structures with surfaces of alternating chemically hydrophobic and hydrophilic material, causing water in their exhaled breath to precipitate out, draining into the esophagus. These structures are largely non-living tissue and continue to function for some years after the warkid dies. Humans have used these to build primitive still-suits, and many desert shelters use these structures to pull water out of all but the most parched desert air.

The true Wark does not deal well with cold conditions, so travelers to the cold Sekta Sea have to try to tame the smaller, undomesticated and far less docile Arctic Shambler. These can be dangerous and unpredictable even when they are apparently very well tamed. Desert travel without Warks is still slightly more dangerous than travel with Arctic Shamblers. This has led to the peoples surrounding the Sekta Sea being among the most primitive and isolated in the known world. The Lesser Mountain Rambler is another species of warkid that has occasionally been successfully tamed, but never domesticated. They are more tractable and predictable than Arctic Shambler and rather faster runners than Warks. All Mountain Ramblers are also excellent mountain climbers.

Thank you for reading,

The Astrographer

Linkfest Wednesday: December 14th

Once again I’ve been doing more research than actual creative work. Don’t tell the boss. As usual, Cornell’s arxiv.org site dominated my research. Also, as usual, the scattered nature of my research mirrors the scattered nature of my brain. So it goes…

On the other hand, in my searches of the net I have found another reliable source for e-prints of useful scholarly articles within my, sometimes odd, fields of interest. The SAO/NASA Astrophysics Data System(aka ADS) is often a godsend.

At one point, I was looking for an article called, “The Internal Composition of the Planets,” written by D.S Kothari in 1936. This was a reference from the readme file of the ever-popular starform program(available here, available and somewhat explained here, improved version here. I’ve been stealing little bits of that program for years(I don’t seem to be alone in that…), so I was hoping to better understand the rationale behind some of the algorithms that program uses. While I like Burdick’s starform and particularly like Jim Burrow’s StarGen, I have a few issues that led me to try figuring out my own methodology. The first simply is I wanted a better understanding of the real science behind the planets I was generating. Secondly, the existing accretion algorithms fail altogether to generate certain kinds of extrasolar planetary systems that we have discovered to be common since the algorithm was created. Notably, the epistellar gas giant. Most importantly to me, I wanted to be able to pass in my own stellar and planetary parameters and have the remaining parameters generated(for instance, start with a particular stellar mass and generate a system or assume the presence of a planet of a particular mass in the habitable zone and generate the environment for that planet). If I didn’t have some issues with accrete and its progeny, this blog likely wouldn’t exist or would at least be considerably different. But I digress…

With my current work on Yaccatrice, I have been very interested in the nature of satellite systems, particularly those of large gas giants. I wanted to do some research into the feasibility of a moon of roughly Earth-like size orbiting a planet of roughly Jupiter-like size in the habitable region of a small red dwarf star. I figured it was unlikely that all of these issues would be covered by any one article, but it was worth a look.

First off I found, “Post-Capture Evolution of Potentially Habitable Exomoons,” by Simon Porter and William Grundy(2011). This article appears to suggest that a gas giant can successfully capture and retain a planet of roughly Earth-like mass. It also leads me to believe that my assumption of a captured satellite taking up a nearly circular low-inclination orbit of about a day in length is plausible. On simulations based on the satellite of a planet of an M0 star of 0.47 Solar masses(larger than, but similar to Cintilla), and a Jupiter-sized planet(smaller than Sky Moon, but also similar), the information in Table 1 and Table 2 on page 4 indicates a survival rate of 23%(not great, but reasonable), and an orbital period of about a day. Not looking too bad for Yaccatrice. Not surprisingly, survival rates are higher for planets orbiting larger stars, although with longer orbital periods for the satellite. More surprising, at least to me, the higher survival rates for captured satellites of smaller gas giants. I’m not at all sure why the Neptune-sized planet seems to show a slightly higher survival rate and, as far as I can tell, the article doesn’t discuss this issue. Maybe the reason is obvious to an experienced astrophysicist?

It looks like tidal heating is so great for a short period that the moon’s surface might even be liquified. This might have some effect on the morphology of the surface(though what that might be after a few billion years, I have no idea), and pretty much assures that any life on the planet would have arisen after the capture event. On the whole this doesn’t change much as I pretty much assumed the capture event would be so catastrophic as to assure total extinction of life on the captured body in any case.

“The 1/1 resonance in Extrasolar Systems: Migration from planetary to satellite orbits,” by John Hadjidemetriou and George Voyatzis(2011) appears to look more at capture. Ultimately, after looking at this a bit, I had to give up and look over the conclusions. It seems to give a fairly low probability of capture, but I really don’t quite understand what this article is saying beyond a rudimentary level. I’ll stick to an optimistic assumption. Anyway, this seems to be discussing a three-body transition for a near co-orbital pair to a planet/satellite system. In the case of the Sky Moon/Yaccatrice system orbiting Cintilla, I was assuming that Sky Moon had an existing system of one or more satellites that were expelled by a momentum transfer event that led to the capture of Yaccatrice. It seems like, depending on the configuration of Sky Moon’s original satellite system and the way in which Sky Moon approached the original orbit of Yaccatrice, this could be a much higher-probability event. For my level of education in the subject, this was a much less useful article than the Porter/Grundy one, but it was tantalizing. I felt like I was right on the verge of understanding something really interesting, but I just never quite made the connection. Too bad, that.

“Pathways Towards Habitable Moons,” by D.M Kipping et al(2009) is a good introduction to the existing literature on the care and feeding of extrasolar moons. In the introduction there is a discussion of the likelihood of Earth-sized moons forming around gas giants(not great), and the possibility of Earth-sized planets being captured as stable satellites by gas giants(better). It goes on to a lengthy discussion as to methods for detecting moons of extrasolar planets and what kind of information can be gleaned by those methods. Some of the details are a little sketchy if you aren’t pretty math-inclined, but it’s just interesting to learn just how much information can be gleaned with the tools we now have. Exciting.

“Massive Satellites of Close-In Gas Giant Exoplanets,” by Timothy Cassidy, Rolando Mendez et al(2009), was written for the purpose of discussing satellites of “Hot Jupiters.” Since the kinds of planets I’m really interested are the kinds where I can get out and take a walk without a spacesuit. Still, I’ve found a few tidbits in the section on tidal dissipation. Formulas 12 and 13 on page 3 give an estimate for the maximum mass of a body which can maintain a stable satellite orbit. For Sky Moon, assuming a Q, or tidal dissipation function, of about 2 x 10⁵, like Jupiter, this comes to about 3.6 x 10²¹ kilograms, or about 0.0006 Earth masses. Disappointing, but in the text it mentions that gas giant Q could be as high as 10¹³. After messing about a bit with the formula, I worked out that a planet a little bigger than Yaccatrice could maintain a stable orbit with a Q as low as 2 x 10⁸. Guess what the tidal dissipation function is for Sky Moon? Another useful formula is equation 21 on page 6 for the effective temperature due to tidal heating.

Cassidy et al(2009) Formula 21

The Q in this case is for the satellite. Assuming the satellite is a, “solid body,” similar to the Earth in structure, a Q_s of about 10 is reasonable. I’ve yet to use this(time constraints), but it could be of interest.

Perhaps the more interesting result of looking over Cassidy et al(2009) has been hunting down some of its references. One thing I found, rather indirectly, was,  ”Q in the Solar System,” P. Goldreich and S. Soter(1966). This was a reference from the starform README which I’ve been hunting unsuccessfully for quite some time. While trying to search for tidal dissipation Q, it just sorta showed up. Yay! Apparently, the day length calculations for starform were based on this. I see that there is stuff in here for the Earth-Moon system, so for future work, I’ll look into this to see if I can refine my rotation period calculations.

I’ve come across a few other nice articles, I’m looking forward to sitting down with. “Formation of the Earth,” by George W. Wetherill(1990). Yeah, that George Wetherill! Okay, maybe that ain’t the kind of name you really want to drop at a cocktail party. Depending on just what sort of nerds you’re making bolshoyeh praz’navoon’yeh with… “How common are Earth-Moon planetary systems?,” by S. Elser et al(2011).  ”Planetesimals and satellitesimals: formation of the satellite systems,” by Ignacio Mosqueira et al(2009). “Tidal Dissipation In Rotating Solar-type Stars,” by G. I. Ogilvie and D. N. C. Lin(2006). “Stable satellites around extrasolar giant planets,”R. C. Domingos, O. C. Winter and T. Yokoyama.