Calidar Map of the Day

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Calidar Map of the Day

Post by Thorf » Wed Nov 13, 2013 7:08 am

Starting from next Monday, I'm going to be posting a new map of Calidar every week day. For those of you who remember the opening months of my Secret Project (which you now know is the Atlas of Mystara project) back in 2005, it ought to be a nice nostalgia trip while at the same time slowly revealing new aspects of the World of Calidar each day.

These maps will preview various areas and features of Calidar, with a focus on the mapmaking process itself. Each week I will feature a different cartographic aspect, and focus on a different area of the world, together with some brief commentary. They will build on each other to present a kind of "making of" feature, like the extras on a movie DVD.

I'm very excited to be able to begin to share what I've been working on for the past few months. Please drop by and join in the discussion. :D

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Re: Calidar Map of the Day

Post by Ambreville » Mon Nov 18, 2013 2:53 pm

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Re: Calidar Map of the Day

Post by Thorf » Mon Nov 18, 2013 3:17 pm

For those who don't have access to Facebook and/or Google+:
(I can't promise I'll post the maps here every day, but I'll definitely come and add them to this thread at some point, probably in small batches, just to keep everything nice and organised.)

Image
The Great Caldera, Equirectangular Projection

The result of a massive collision in Calidar's ancient history, the Great Caldera is a perfect circle with a mountainous rim. This presents a unique mapping challenge: drawing a circle on a sphere is easy, but the rectangular map projections usually used to design worlds are another matter entirely.

The 2:1 latitude/longitude grid known as Equirectangular, Plate Carrée, or simply Geographic Projection is very useful because it is easily applied to 3D spherical models, such as Google Earth. But the further north or south you go, the more stretched it becomes, until the entire top and bottom lines of the map represent the single points of the poles.

The Great Caldera stretches from 25º to 65ºN, putting the northern part of the Caldera in an area which is very susceptible to these distortions.

Look closely at the map. Does it look like a perfect circle to you? Probably not. But in fact it is a perfect circle when viewed on a globe.

The next map provides a view of the Great Caldera which better illustrates its true shape.

Image
The Great Caldera, Stereographic Projection

This companion map shows the exact same coastal outlines as the first map, but using a more suitable projection for a circular area.

The Stereographic Projection is particularly appropriate for the Great Caldera, because it shows a circle on the globe as a circle on the map.

If we had just drawn a circle on the Equirectangular Projection base map, it would have ended up being deformed when viewed on a globe. These days, when it's very easy to set up Google Earth or a number of other programs to display interactive globes in the computer, it was a design priority to get these projection issues right from the start.

Getting back to the map, you can see how the perfect circle of the Great Caldera has collapsed and decayed at various points. Later in the week, we'll take a look at the design phase for the mountains encircling the Caldera.

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Re: Calidar Map of the Day

Post by Chimpman » Mon Nov 18, 2013 5:20 pm

Awesome maps, and great explanations here Thorf! No questions right now - everything you've said makes perfect sense. I'm really happy that Calidor is being designed with these mapping issues in mind.

I'm really looking forward to seeing some of the design insight into how and why you guys created portions of the map. Can't wait for the next installment on mountains.
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Re: Calidar Map of the Day

Post by Thorf » Tue Nov 19, 2013 9:20 am

Map of the Day Number 3
Image
The Great Caldera (Uncorrected Version), Equirectangular and Stereographic Projections

The first two maps show the final, corrected version of the Great Caldera. It only looks circular in the Stereographic Projection, of course, but place the Equirectangular Projection on Google Earth and it will become circular again.

Today's map shows the same design for the Great Caldera, this time as a political map showing borders and country names. The inset shows the original design, which we did on an Equirectangular Projection (as many mappers do, since it allows the aforementioned use of Google Earth). It looks fine - a perfect circle. The problem with this is that when it is applied to a globe or other 3D spherical model, the Caldera's shape is deformed, appearing more like it looks in the Stereographic Projection.

We will continue to look at the effect map projections have on the shapes of Calidar's landforms over the next few weeks. But before that, join us again tomorrow as we start to delve a little deeper into the terrain design, starting with the mountains, and then moving on to height maps (of which more later).

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Re: Calidar Map of the Day

Post by Big Mac » Tue Nov 19, 2013 12:18 pm

One thing I wonder. If I was on a ship flying through space above the middle of the Great Caldera (maybe between Araidur and Phrydias) and I looked down, would I see a circular shape from there?

Some of these variant projections seem to be distorting the shape from a circle to more of an ellipse or even an egg-like shape.

I'm no expert with cartographic projections (although I wish that I knew more). I know they all distort the data in different ways, so that one will "lie" about one part of a world, but "tell the truth" about another part.
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Re: Calidar Map of the Day

Post by Thorf » Tue Nov 19, 2013 1:42 pm

David, the answer is a resounding yes.

The Stereographic Projection is a conformal projection, which means that it preserves shapes. There are various other conformal projections, of which Lambert Conformal Conic is the most useful for Calidar (and probably for real world maps, too - although this is a huge generalisation). You'll be seeing maps with it very soon.

But I suspect that what you really want to see is the Orthographic Projection, also known as "view from space". That's essentially what you see on the screen in Google Earth. Are you familiar with the Times Atlas of the World? It uses an Orthographic view with satellite imagery to introduce each continent's section.

Getting back to the topic, the rectangular projections such as Equirectangular and indeed Mercator unavoidably stretch things as they approach the poles, simply because there is less land there to map on a sphere or ellipsoid. This is not necessarily bad, and certainly not wrong. But it's not very useful if you want to see the "true" shapes of landforms.

For Calidar, the base map is Equirectangular, but that projection will likely not appear in any of the published maps. It may well appear online as the net for a 3D interactive globe, or simply for use as an image overlay in Google Earth. The main projections for continental maps are Stereographic (and Polar Stereographic for the poles), Lambert Conformal Conic, and Mercator. Stereographic is useful for circular areas, as well as areas that spread out in all or most directions. Lambert Conformal Conic is useful for areas that spread out east-west. Both of these are used for areas away from the equator; Mercator is best for areas near the equator, where there is very little distortion in that projection.

Hex maps are another matter, and I haven't quite decided what projection(s) to base them on yet. I can tell you that it will not be Equirectangular or Mercator if the regions involved are not close to the equator. The decision will be based on what feature to render true in those maps: conformity (shape), area, or some other factor. Especially considering that Bruce uses the hex maps to calculate demographics, I'm strongly considering going with area-preserving projections.

There's a great article about projections and how to choose the right one for your map here. Highly recommended reading, and the tables at the bottom of the article are exceedingly useful.

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Re: Calidar Map of the Day

Post by Gecko » Tue Nov 19, 2013 5:36 pm

I notice the dashed line on the newest map, is that the northern tropic? and if so, is the planet size and axial tilt similar to earth's? (I'm still trying to get a sense of scale here)

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Re: Calidar Map of the Day

Post by Thorf » Wed Nov 20, 2013 8:14 am

Map of the Day Number 4
Image
The Great Caldera Mountain Design, Stereographic Projection

Here's a look at Bruce's design for the mountains of the Great Caldera. You can see how they generally follow the outside of the circle, forming a gigantic rim around the ancient impact crater. Time has worn it down, and it is broken in a number of places.

Bruce drew these lines as guides for constructing a full height map (also known as a bump map or elevation map) of the area. I took the lines, blurred them, messed them up a bit, and converted them into uneroded mountains.

Next, I took the same lines and expanded them out, messing them up in a similar way to create hills.

Come back tomorrow for a look at the resulting height map.

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Re: Calidar Map of the Day

Post by Thorf » Wed Nov 20, 2013 8:22 am

Gecko wrote:I notice the dashed line on the newest map, is that the northern tropic? and if so, is the planet size and axial tilt similar to earth's? (I'm still trying to get a sense of scale here)
Yes, that is indeed one of the tropics.

Calidar is just a tad bigger than the earth, at 43,200 km (27,000 miles) circumference. Its axial tilt is 23.5º, which is roughly the same as the earth's. Its rotation period is 24 hours, and orbital period is 365 days. In a lot of respects, it's very similar to the earth, so you can expect similar weather patterns, climate, and so on.

I mentioned in another thread that you can calculate distances from earth maps by multiplying by 1.0779783324858. This is especially useful when using Google Earth with a Calidar world map overlay, and it allows measurements to be made using this and other software designed for the real earth.

Hmm... Would you be interested in seeing this in action? I can't reveal the world map yet, but I can post a world map showing just the Great Caldera in its correct position - probably as a Google Earth KMZ file.

There are other maps demonstrating comparisons with real world areas in the Map of the Day pipeline, too. :D

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Re: Calidar Map of the Day

Post by Gecko » Wed Nov 20, 2013 10:45 am

Thanks Thorf,

I see now above I had missed where you mentioned:
The Great Caldera stretches from 25º to 65ºN
with that information (which I had missed previously :oops: ) and your confirmation that the planet is more or less earth like (size wise; tilt; and confirmation that that was the northern tropic), I'm getting a rough idea.

I also take it then that the Black & White Day one & 2 maps have lat. & long. marked every 5º,
& the Black & White Day four has both marked at every degree (1º intervals), but the colored Day 3 is different, it looks like the lattitude is marked in 10º intervals, but the Longitude (#º's E-W) is what? every 20º?

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Re: Calidar Map of the Day

Post by Thorf » Wed Nov 20, 2013 11:06 am

Mostly right! You got Maps 1, 2 and 4 spot on, but Map 3 is a little harder. It has both latitude and longitude marked every 15º. If you compare the location of the Great Caldera in relation to the graticule lines between Maps 2 and 3, you can clearly see how deformed it was before we corrected it.

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Re: Calidar Map of the Day

Post by Gecko » Wed Nov 20, 2013 10:04 pm

Thorf wrote:Mostly right! You got Maps 1, 2 and 4 spot on, but Map 3 is a little harder. It has both latitude and longitude marked every 15º. If you compare the location of the Great Caldera in relation to the graticule lines between Maps 2 and 3, you can clearly see how deformed it was before we corrected it.
Your right, 15º would make sense for the degree's North-South, but if that's the case, then from eyballing it along the central graticule that runs through Arajðûr, it looks like the land mass [plus the central waters] on the colored map (#3) covers somewhere between 35º or at most 40º East to West, but on the Black & White one's they look like they are at least 50º, probably somewhere more around 55º or more East to West - or is that due to some sort of distortion on stereographic projections that I've overlooked? (I hated my college course work on Stereographic transformations - While I understand the concept and benefits perfectly well, the implementation I found extremely confusing)

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Re: Calidar Map of the Day

Post by Thorf » Thu Nov 21, 2013 3:06 am

That's the whole point: Map 3 is wrong. It shows what would have happened had we just drawn the Great Caldera onto the base Equirectangular Projection and left it as it was.

Hmm, this gives me an idea for a way to improve Map 3...

Image

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Re: Calidar Map of the Day

Post by Thorf » Thu Nov 21, 2013 3:32 am

Map of the Day 5
Image
The Great Caldera Uneroded Height Map (First Draft), Stereographic Projection

This is the first of two maps today. The second will be posted later.

Following on from yesterday's mountains, this is the fully detailed height map I constructed from Bruce's mountain design.

A word about height maps: this map shows elevations, with white being the highest point, and black being the lowest - in this case, sea level. It takes some imagination to understand what's going on, but basically speaking the white points are mountain peaks, while the grey lines in between them are valleys, and the darker grey to almost black areas are hills and plains.

You may be wondering why such a map is necessary or even desirable. The answer is that this map can be loaded into terrain viewer programs, which show it as a 3D model of the terrain. Many computer games use these models to construct their worlds, and just as in those games, it's possible to move around and explore the landscape.

Moreover, the altitude data can be used in conjunction with the latitude to calculate the climate, and even to help texture the world accordingly.

Height maps form the basis of all of Calidar's maps, and they open up exciting new possibilities for Calidar's cartography and art.

Come back later today to see another view of this map, which should make it a little easier to visualise. At the same time I will also introduce the topic of erosion. See you then!

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Re: Calidar Map of the Day

Post by Le Noir Faineant » Thu Nov 21, 2013 6:28 pm

Is it just me, or... Lufiaaaaaaa? :D

http://www.time4rpgs.net/wp-content/gal ... _world.png (Caution, big.)

I can very well live with that similarity, by the way! :)

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Re: Calidar Map of the Day

Post by Gecko » Thu Nov 21, 2013 7:05 pm

Thorf wrote:That's the whole point: Map 3 is wrong.
oh..... :oops: I had completely missed that point, now I follow you, sorry

and good-catch / great-work in doing all this background work to make it realistic. I bet there's not another game world out there that put in that kind of effort.

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Re: Calidar Map of the Day

Post by Ambreville » Thu Nov 21, 2013 10:07 pm

Le Noir Faineant wrote:Is it just me, or... Lufiaaaaaaa? :D

http://www.time4rpgs.net/wp-content/gal ... _world.png (Caution, big.)

I can very well live with that similarity, by the way! :)
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Re: Calidar Map of the Day

Post by Ambreville » Thu Nov 21, 2013 10:08 pm

Gecko wrote: (. . .) I bet there's not another game world out there that put in that kind of effort.
Thanks!
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Re: Calidar Map of the Day

Post by Big Mac » Fri Nov 22, 2013 1:14 am

Thorf wrote:Hmm, this gives me an idea for a way to improve Map 3...

Image
Why didn't you just say that in the first place! ;)
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Re: Calidar Map of the Day

Post by Thorf » Fri Nov 22, 2013 1:39 am

Big Mac wrote:Why didn't you just say that in the first place! ;)
I probably should have, but it only occurred to me upon reading Gecko's comments in this thread.

I did actually say something to this effect in the commentary, but I'm a little worried that my commentary has been too technical, resulting in a lot of people tuning out. :(

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Re: Calidar Map of the Day

Post by Thorf » Fri Nov 22, 2013 1:41 am

Map of the Day Number 6
Image
The Great Caldera Uneroded Height Map (First Draft - Shaded), Stereographic Projection

Here is today's second map. It's exactly the same as map 5, but instead of displaying low-to-high elevations as black-to-white, it uses a colour scheme to shade each height. This helps to see what exactly it is that's being depicted, but you have to bear in mind that the colours represent height variations, not terrain types.

Blue is sea level, light green-to-darker green is lowlands, light brown-to-dark brown is progressively higher areas, and dark brown-to-white is highlands.

Generally speaking, the lowlands are flatter than higher areas, so it's relatively safe to assume that green areas are lowland plains, or at most rolling hills.

Now, as I mentioned with map 5, this height map is uneroded. That is to say, it has not undergone simulated erosion to carve mountains and valleys into those mounds. This is a multi-stage process which takes anything from a few hours to a few days, depending on the size of the area and the resolution it needs to be done at. This model is roughly 0.5 km per pixel at full resolution, and the full image is 9,999 x 9,998 pixels. This provides a good level of detail for continental mapping, though not enough for country-level maps.

The fully eroded version of this map is the Great Caldera map with borders and labels which Bruce revealed first - currently our profile picture. Come back tomorrow to see a clean version of the fully eroded first draft of the Great Caldera.

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Re: Calidar Map of the Day

Post by Thorf » Fri Nov 22, 2013 1:19 pm

Map of the Day Number 7
Image
The Great Caldera Eroded Height Map (First Draft - Shaded), Stereographic Projection

Here it is: the first draft of the Great Caldera's fully eroded height map. Compare it with yesterday's pre-erosion map, and you can plainly see how the white blobs have been carved into majestic white peaks. What was previously a landscape of blobs has become a proper landscape of plains, hills, mountains and valleys.

At this point it becomes very clear why the Great Caldera's borders are located where they are - the political divisions follow natural divisions in the terrain, which split the land of the Caldera into numerous smaller areas.

Note that this is the first draft; there are various problems with this map, and in fact there have been another three passes since this map was completed. I'm quite happy with the fourth draft, so it may well become the final one.

I'm sure many will be impressed with this, but I'm equally sure that some may be thinking: so what? Why is this useful? Why don't you stop talking about things and just show us the finished maps?

Don't worry, we'll get to some major reveals very soon. In the meantime, I am preparing one last preview image to round out our week. I'll post it as soon as it's ready. It should demonstrate quite elegantly why I have chosen to develop Calidar's terrain in this way.

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Re: Calidar Map of the Day

Post by Thorf » Fri Nov 22, 2013 1:20 pm

Map of the Day Number 8
Image
3D Views of the Great Caldera, based on Eroded Height Map (First Draft - Shaded), Stereographic Projection

Here are two very simple 3D views of the Great Caldera's terrain. They demonstrate the huge benefit of height maps, which is to say that they are really 3D models. Using these very same height maps, it is possible to generate photorealistic-looking landscape views.

But for now, this is not our goal; the first priority is of course to establish the terrain and its shapes by producing high quality maps of the area. The height maps help in this, too, by allowing the correlation of altitude and latitude data for climate shading.

The shading you see here is a simple elevation-based shading. Note how the flat map's colours have been adopted into the 3D view. It's actually possible to load any map as a texture for the 3D model, so even without photorealistic rendering, you can expect to see more of these 3D views - and prettier ones, too.

More about all of this later. This brings us to the end of our first week of Maps of the Day, exploring the Great Caldera, the heart of the World of Calidar. Thanks for reading! Join us again next week as we preview the shape of the Dread Lands which lie outside the relative safe haven of the Great Caldera.

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Re: Calidar Map of the Day

Post by Havard » Fri Nov 22, 2013 6:25 pm

Great maps so far Thorf!

Love the Wrong Wrong Wrong one. The VotPA reference did not escape me! :)

The latest 3D map is nice, but perhaps you could have used a different shade of green?

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