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Javen
05-21-2010, 01:49 AM
Alright, so I just posted an introduction, but I feel like this is an ideal time to ask this question.

I work on a Mac, which obviously brings with it the problem of not being able to use FractalTerrains. I've achieved decent results with running the "Lighting Effects" style of elevation (shadows and light, full mountainous, ect), but it really doesn't achieve the effect I'm looking for...which is something similar to what a2area did with his map.

To put it simply, I would like my maps to have the effect that real height maps and high-quality terrains have: a sloping effect...something I could put into Bryce and see a good-looking, natural-looking mountain instead of a couple smooth bumps and a wide span of flat ground.
I'm not expecting the same results as a dedicated program, but I was wondering if anyone had any ideas about how someone would achieve maximum realism with what I have? I've heard there are DEMs provided by the government that do something similar, but so far I have yet to find any.

waldronate
05-21-2010, 03:28 AM
Is there a part of the world that has the kind of topography that you're interested in? What scale are you looking for? A couple of miles accross, 20 miles, 100 miles, 1000 miles?

Javen
05-21-2010, 03:35 AM
I'm using this for a map of islands with a similar terrain profile to the Greek islands.

I'm not sure about the scale. It's large, though, as these islands are roughly Indonesia-sized, hence why I'm interested in very large, complex mountain ranges...because there are several mountains in this area.

waldronate
05-21-2010, 03:37 AM
Grab some DEMs and a photo-editing tool like Photoshop or GIMP and get to cut and pasting! jwbjerk had a good tutorial on the subject recently (using the detail from a real-world DEM to modulate a basic low-resolution painted DEM). http://www.cartographersguild.com/showthread.php?9919-WIP-This-Orb-world-building-and-mapping-project/page2 has the initial description of the technique.

http://www.vterrain.org/ has some good links to data sources if you poke around a bit.

Javen
05-21-2010, 03:52 AM
Thanks for that link. It is an interesting idea I'll have to try out tomorrow when I am working. It will definitely solve the problem of trying to take my already-made topological maps and adapting them to work with a political one.

One thing I have trouble understanding is why it appears the DEMs on that site are reversed. The Rockies are presented as the lowest point. I think, though, with http://www.shadedrelief.com/natural3/pages/extra.html, I should be good.

Thanks for all your help, waldronate.

jwbjerk
05-21-2010, 10:14 AM
One thing I have trouble understanding is why it appears the DEMs on that site are reversed.
Is there a standard convention for either white or black being the highest? I think i've seen i both ways.

waldronate
05-21-2010, 03:36 PM
The color mapping is a function of how the displaying software wants to do it. The traditional technique assumes a grayscale mapping with lowest = black and a fixed upper value such as 255 = white because that's how the hardware operated. However, these days it's a virtually free operation to map an input range into any set of colors you like (including the rainbow hue-based scale preferred by some groups). Generally speaking, though, the DEM itself is usually mapped with real-world units (something like a 0 value in the DEM is 0 meters altitude, 1000 in the DEM is 1000 meters above sea level, -1000 is 1000 meters below sea level, etc.) in the case of 16-bit data. 8-bit data has no particular standard because it has only 255 possible levels and most DEMs need more than that.

The Natural Earth series are very nice dataset. Tom Patterson does excellent work. It's got all the holes cleaned up and some of the worst errors removed. The main texture maps are also an excellent resource for coloring as long as you keep things at roughly the same type of climate.

Javen
05-24-2010, 10:24 PM
Alright, so I've been working with these height maps and achieved good results from a simple colour-based topography map perspective. However, I still have trouble rendering the natural features into beveled height maps.

Has anyone tried turning these DEMs into raised satellite-style mountains that might be able to offer some advise? So far as I've seen, rendering river paths and erosion aren't particularly hard, but making a gradient map and accurate bevel and emboss settings is proving difficult.

Would someone with more experience on making DEMs into beveled terrain maps mind providing some enlightenment on the matter?

jwbjerk
05-25-2010, 12:44 AM
Javen, i'm not sure exactly what you want to know.

Here's how i use DEM elevation on my project. (http://www.cartographersguild.com/showthread.php?10304-How-to-Apply-Realistic-Elevation-from-Real-Maps-to-Yours.)

I use photoshop's lighting effects give shading to my greyscale hight map. It's not dynamic, i.e. you have to re-render the lighting effect each time you change something, but i think the results are much better than anything you could get with bevel and emboss.

Javen
05-25-2010, 12:54 AM
I'm a little confused about that part that you're mentioning...in your tutorial, there is no mention of lighting effects. I considered it, but failed to achieve any results I really felt comfortable using.

Do you have a specific lighting effects setting that you've found works well?

jwbjerk
05-25-2010, 01:41 AM
I'm a little confused about that part that you're mentioning...in your tutorial, there is no mention of lighting effects. I considered it, but failed to achieve any results I really felt comfortable using.

Do you have a specific lighting effects setting that you've found works well?

The tutorial explains how i make the greyscale elevation information.

However it sounded like you wanted information on the next step: how to turn that elevation information into something that looks cool. That's where lighting effects comes in for me-- number three in this picture (http://www.cartographersguild.com/showthread.php?9919-WIP-This-Orb-world-building-and-mapping-project&p=107982&viewfull=1#post107982).

* The trick is to take your grey scale elevation and copy it into a new channel.
* Make a medium grey layer above all your other layers and set the blend mode to overlay. This is the layer you'll do the lighting effects to.
* Choose the elevation channel you just made as the "texture channel" at the bottom of the lighting effects dialog. Also make sure your light is "Directional". The rest you can tweak as you like.

Javen
05-25-2010, 01:56 AM
Thanks for the insight, jwbjerk. I think I've got what I need to make it work now. Thanks as well for dealing with my confusion and taking time to show me how you did it. I'll be sure to credit you if I ever manage to finish this.