Modeling a landscape
When modeling a landscape, the best method to use involves a Displacement map, that deforms a Plane in such a way, that higher and lower areas (mountains and valleys) are created. Let's start with creating a Displacement map in Photoshop:
I have created the basic structure of my landscape on a 500x500 pixels image. Low land is in black, whereas the white areas define where mountains should arise. You should only draw the general height difference, we will fine-tune it later in MAX. Image 1 shows the rough outline of the landscape: a (black) valley in the middle, that rises up to the sides (white).
1. The basic model: Create a Plane (R3 only, 2.5 users will need to use a Box) in the top viewport. Set its extents to 1000x1000 units and give it 30x30 Length/Width Segs. If You need to use a Box, use the same parameters, but it must not have any height. Apply a Displacement modifier to the created plane. Then click on "Map" (not "Bitmap") in the "Parameters" rollout, and choose "Bitmap" from the window that appears. From its parameters, choose the rough displacement map You made in Photoshop. To give the whole its actual height, change the "Strength" value to 200. You now have a rough landscape effect. To keep the landscape level, You should check the "Luminance Center" option.
Open the Material Editor and put the Displacement map from the plane's modifier stack into the diffuse channel of a material, choosing "Instance" when prompted for a duplication method. Apply this material to Your landscape. Now we will add details to our Landscape, to make it look more interesting. To do this, we will first increase the number of segments in our plane. This is simple enough for R3 users: simply go back in the modifier stack to the plane, and increase the "Render Segs" parameter to a value of 12. This subdivides the plane at render time, whereas the viewport model remains at a low-polygon level. 2.5 users need to use a different method: Apply a Meshsmooth modifier, and set change its operation to render-time only by changing the light bulb (at the top of the rollout) accordingly. Then increase the "Iterations" parameter to 2 or 3 (the higher this value, the more detail the Landscape can display). This gives You (almost) the same result as with R3, but with somewhat more work.
2. Details using a Noise map:
Make a test render. Your landscape should look somewhat like the one n Image 2. Now to add more detail: Go back to the Material Editor and to the diffuse map. Click the "Bitmap" button next to "Type:", and elect "Mix" from the list of map types. In the window that pops up, select "Keep old map as sub-map". You have now made the rough landscape map part of a mix map (this also applies to the displacement map in the modifier stack, as we made an instance!).
You've now got thousands of possibilities to further change the landscape (oh God, how to explain this one??): Your landscape map is in the "Color 1" channel. Change the mix value to 40, and click on the available "Color 2" map channel. Choose the "Noise" map type from the list. You're now at the Noise map level. Change the type of noise to "Turbulence" in the Noise Parameters rollout. Give the noise a size of 60, set the "High" noise threshold to 0.4 and the "Low" noise threshold to 0.1. Change the number of levels to 5. Now to change the colors: Set color 1 to a light gray, and color 2 to white. Those are the settings I used.
If You haven't had much experience with the "Noise" map, play around a little with the different values. Change the values only a little at a time and make test renders to see how the landscape changes. For example, take the size of the noise map and double it. Instantly the Landscape has gotten a different look to it. Play around with the high/low threshold values: These have a large effect on the result, especially with the turbulence noise type. You can change the look of the landscape completely with these. Lastly, the mix value, that determines how much the noise map is mixed in with the original "Photoshop-Landscape" map, also has a high impact on the end -result.
Whether You use my example values, or make Your own landscape... What's important is: The basic structure of the landscape that You made using Photoshop, is preserved. Mountains and valleys are apparent in the model. The dimensions (huge Alps, or calm hills) are controlled by the noise map. My landscape now looks like that in Image 3 (the Mix map made everything a little flatter, but that's ok - You can always increase the strength of the Displacement map again).
Back to Photoshop:
Now on to texturing. To make Your landscape look good, You should be able to tell the difference between flat areas (grasslands, snow-covered areas) and step cliffs. We need a map that clearly shows this. I call this an Inclination map (white=steep cliffs; black=flat areas). To create such a map, render a top view first. The bigger the render, the better; the detail of Your landscape depends on this. I rendered an image at 2000x2000. Make sure You applied the Displacement map as a Diffuse map to the landscape as well. Change the self-illumination of the material to 100 (un-check the "Color" option!), so that the landscape is not affected by the default lighting in the scene¹. Save the rendered image as "Inclinationmap.tga" (See image 4).
Open the Inclination map in Photoshop, and clip it to its boundaries (with that I mean, get rid of any black edges around it), in order to be able to map it back onto Your landscape perfectly later on. In case your map has fairly little contours (like mine), You could increase the contrast by using the Tone values (non-Photoshop-experts can simply use Image > Settings(?) > Auto contrast).
Then choose Filter > Stylize(?) > glowing outlines. Play around with the values a little, so that You get a result like that in Image 5. This filter allows us to visualize any contrasting areas: A strong contrasting area in the Inclination map (a steep cliff in the displacement map) will become white. Low contrasting areas, i.e. areas with little change in colors (= little change in height in the Displacement map) will become black.
Optionally, You could apply another tone correction to the new image, to increase the contrast a little further. Save this map as "Inclinationmap2.gif" (to save space).
The landscape's texture:
Now back to MAX. We need two textures: one for the flat areas (say, snow), and one for the cliffs (where the snow won't stay). I won't describe here how I made the two textures. Simply check those out from the example MAX file. Let's assume You made two different types of textures (snow and rock). Now all You need to do is mixing these two together using the inclination map, and applying it to our landscape. To do this, make a new material in the Material Editor, and choose "Blend", not "Standard" as the material type. Blend is similar to the Mix map, but here You can mix complete materials, not just two textures.
Put the snow material in the first channel, and the rock material in the second. As a Mask, choose "Bitmap", and pick the Inclinationmap2.gif as the file to use (should the snow and rock be the wrong way around, check the "Invert" option in the mask bitmap's "Output" area).I have then added a sky and some fog to the scene. Done. The whole effect is made or broken by the texture.I The inclination map should make sense on the model (it's a little off in the example scene) If You think it's not quite right, it's back to Photoshop and trying the procedure again with different values (isn't that much work). The texture of the rock is also of high importance. Check out the tutorial for making rock materials for more information.
Addition (May 24th 2000)
There's also a freeware plugin that completely eliminates the need for an Inclination map. The Terrain Material from Johnny Ow (www.bigpixel.com) makes the whole thing a lot easier. Put the plugin in Your MAX Plugin directory, and it will show up in the Material Editor next time You start MAX.
Have fun!
¹ Note from translator : You will also need to set the Shininess/Shininess Strength parameters to 0.