quick relief with painter

"No flat maps!" can be the battle cry of desktop mapmakers with the battery of software tools and elevation data available today. Software like Bryce, VistaPro and Natural Scenery Designer are specifically designed to render 3D-style images of terrain. Even graphics workhorses like Adobe Photoshop and MetaCreations' Painter permit mapmakers to create full-color terrains. Painter is particularly adept at rendering relief with a minimum of steps, and is the subject of this article.

preparing to paint
Painter makes mountains from grayscale-to-height (G2H) images. The first step to making a G2H image is to acquire a digital elevation model (DEM). You can download free DEM data from the following URL's:

• edcwww.cr.usgs.gov/doc/edchome/ndcdb/ndcdb.html
• edcwww.cr.usgs.gov/landdaac/gtopo30/gtopo30.html

A DEM file contains rows of elevation values. DEM-reading software is needed to turn these values into grayscale pixels. Several shareware or freeware programs perform this task:

For Windows-

• DEMvert (www.cs.purdue.edu/homes/beemanaj/DEMvert/default.html)

For Macintosh-

• DEMview (www.terraformers.org/DEMview.html#downloadDEMview and also available from the CD accompanying Susan Kitchen's Real World Bryce book)
• DEM Reader (home.san.rr.com/bwagner/DEM_Reader.html).

The G2H output of these programs is an image whose dark-to-light gradation represents a low-to-high elevation gradation.

G2H image based on USGS DEM data

If you plan to tile several images together, you will need to "equalize" them. Equalization assigns each file a grayscale range based on the elevation range of the complete set, ensuring that the same elevation among different G2H images is mapped to the same gray value. Most DEM-reading software allow you to manually or automatically equalize images.

landscape painting
With G2H images in hand, enter Painter. If you need only a grayscale relief, go directly to the Select Effects>Surface Control>Apply Surface Texture menu (discussed below). Otherwise, your first step is to create a dark-to-light color gradation to replace the G2H's grayscale range. Choose an existing gradation from the Art Materials>Grad palette and select Grad>Edit from the top of the palette. When the Edit Gradation dialog menu appears, click on the color wheel back on the Art Materials palette. Click a triangle marker below the gradation bar and then click a color from the color wheel.

Edit Gradation menu with a custom-built gradation

You can create gradations with as many colors as you want. Be careful to maintain a dark-to-light transition in the gradation. If you include a dark color in the middle, your terrain will have craters and sunken plateaus instead of smooth slopes and peaks.

You can save gradations for future use. Try different color components to lend the gradation a geographic theme--browns for deserts, yellow-greens for tropical terrains, and cool blue-greens for lands in the northern latitudes. Integrate the relief with the rest of a publication by borrowing gradation colors from other graphics or photos.

The final step to colorizing the image is to select Grad>Express in Image from the Art Materials palette. A pop-up menu presents a "Bias" function; use the slider to spread the lightest colors across more of the image area.

The G2H image colorized with the color gradation

making mountains and molehills
Now you're ready to build the terrain image. Go to the Apply Surface Texture menu located under Effects>Surface Control. In the menu's Material controls, select Using> Image Luminance and click the Invert box. If the terrain appears inverted (river valleys look like sinuous ridge tops), deselect Invert. Use the Softness slider to blur unwanted terrain details and generalize the terrain.

The Amount slider builds the terrain by pulling shadows and sunlit slopes out of the image. Slider values between 20% and 100% will produce realistic relief. You should moderate Amount to keep the image in line with the ruggedness of the real terrain, and to keep shadows from overtaking the image (and possibly interfering with type and map symbols on an overlying map).

The Apply Surface Texture Menu

Other menu options affect lighting conditions. You can reduce glare on steep slopes by moving the Shine slider to values between 0 and 20%. Experiment with the menu's Lighting Controls. Decrease the Conc value to brighten the image. You can adjust terrain colors by changing the Light Color from white to a yellow, blue or red. Keep the Light Direction settings set to a northwest sun position to display the optimal 3D terrain effect.

Scroll around the Preview window to see how well your menu settings affect areas of high and low elevation in the terrain. When satisfied, click Okay.

The resulting relief image

finishing touches
Painter provides many tools to alter color and tone, and add special effects. One effect-adding a paper grain texture to an image-solves a common relief problem. Look at the left side of the image below. Notice that the terrain is so gentle here that Painter has raised portions of it as layer-cake plateaus. In the right side, a paper grain texture has been added to roughen the surface and hide the elevation transitions.

On left, a layer cake effect-on right, same area after adding paper grain texture

To add texture, begin by selecting a paper grain from the Art Materials palette. Adjust the texture Scale to make granularity finer or more coarse. Enter the Apply Surface Texture menu and select Using Paper Texture. Use the Apply Surface Texture preview window to gauge the color and tone changes that the texture creates, and adjust the menu's controls accordingly. Setting a very small Amount (under 20%) is usually sufficient to hide the layer-cake effect, and to give the terrain an overall appearance of detail. Be careful not to set the Amount so high that the texture's tiled pattern becomes visible.

With Painter's masks and floaters, you can carve out sections of the relief and graphically accentuate National Forests, parks or urban areas. In the image below, a vector boundary was imported from Adobe Illustrator, converted to a selection, and a section of the terrain floated as a new layer (floater). Color correction adjustments and a drop shadow were applied to the floater, while the surrounding terrain was lightened.

A park area pulled out from the surrounding terrain

final word
Painter proves a worthy addition to the mapmaker's tool chest. It renders a terrain with fewer steps than other programs. While it can't create oblique views like Bryce, it is also not constrained by image size or resolution. As you work with Painter, you'll find that its preview windows and multiple undos allow you the creative freedom to find just the right color and effect for any terrain map you need.


Steven Gordon's web site at home.earthlink.net/~gordonmaps presents samples of his relief, tourism and publication maps. Steven welcomes comments on this article via gordonmaps@earthlink.net.

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