This tutorial introduces a technique using Bryce and Photoshop software
to bring the 3D terrain depiction found on panoramas to ordinary
planimetric (flat) maps. The technique gives cartographers an
alternative to traditional shaded relief for presenting terrain at
small-scales (Figure 1).
Figure 1. Planimetric maps in the Albers Equal-Area Conic Projection shown with traditional shaded relief and 3D relief. Illumination emanates from the northwest on the shaded relief and from the southwest on the 3D relief, the optimal illumination direction for each method of relief portrayal.
The use of 3D relief on planimetric maps has a long history. The
earliest known map, a 5,000-year-old clay tablet from Mesopotamia,
depicts mountains in profile with simple hump-shaped mounds, a style
that remained popular in various forms up until 19th century. "Reliefkarte
der Centralschweiz" (see the bottom image) created by Xaver Imfeld
of Switzerland in 1887 shows the style at its most refined level.
Compared to shaded relief, which assumes a theoretical viewpoint directly above the earth, 3D relief shows landforms “standing up” in partial profile. Because 3D relief closely resembles how mountains appear to humans on the surface of earth, it is easier for people to understand at a glance. High solitary mountains, such as Mt. Fuji and Mt. Kilimanjaro, which are all but invisible on a shaded relief map from above, actually look like the spectacular mountains that they are when viewed obliquely in 3D.
Despite the advantages of 3D planimetric relief, it is rare today. During the last two centuries as cartography became a formal profession, 3D relief has fallen out of vogue in favor of more scientific and accurate methods of relief portrayal. The technique does indeed have its shortcomings. Because 3D relief shows only the south-facing slopes of prominent topographic features (on north-oriented maps), information is lost. This problem is most critical at large scales rather than small. Not seeing the north facing slopes of, say, the Grand Canyon on a 1: 5,000,000-scale map is not a major issue—at such small scales hidden areas comprise only a tiny percentage of the entire map and understanding the overall topography of the Colorado Plateau is a design priority. By contrast, at larger scales areas hidden by 3D relief can account for a much higher percentage of the total map area. Hiking the Grand Canyon with a 1:25,000-scale map that does not show the cliffy slopes below the South Rim would not do. Furthermore, 3D relief conceals the glaciated north faces of high mountains in the northern hemisphere, which are usually the most dramatic and recognizable.
Another shortcoming of 3D relief presented on large-scale planimetric maps is one of confused identity. As neither a panorama nor map, these products simply don’t look right. At large scales one expects to see evidence of perspective—background haze or terrain diminishing in size with distance—that is not present. Fortunately, for our purposes, at smaller scales our eyes are accepting of this hybridized depiction.On small-scale planimetric maps 3D relief depiction is best suited to physical base maps with minimal line work and thematic information. A map showing the meandering route of a traveler through various countries would be an appropriate use. The technique excels at showing physiography. During the mid twentieth century, Erwin Raisz of the US and Heinrich Berann of Austria, with their famous and widely differing styles, used 3D planimetric relief with great success to present topography on small-scale physical maps (Figure 2).
2) In the Document Setup dialog (File/Document Setup) deselect the Constrain Proportions button and set the Document Resolution (which determines the size) to a square shape that fits entirely on your monitor.
3) Select and delete the default plane in the Bryce scene.
4) In the Sky and Fog palette:
A. Select Simple Black Background as the sky color.
B. Change the Shadows setting from 90 to 0 to eliminate cast shadows from the scene.
5) Double click the large Camera Trackball and set the FOV (Field of View) setting to 1, the lowest value possible. Doing this removes most of the perspective from the Bryce scene. It also makes objects in the scene appear much larger, so you will need to repeatedly push back on the Z dimension using the XZ Camera Control arrow until the entire scene fits inside the square Bryce document window.
6) Go to File/Import Object and import a square PGM terrain and use the Camera Trackball to orient the terrain north and set the viewing elevation. It should appear similar to the foreshortened terrain shown in Figure 4, left.
Note: The Bryce setup file I provide automatically orients imported PGM terrains to the north (assuming that they are north oriented to begin with) and sets the viewing elevation to produce 3D terrain that “looks right” at small map scales.
7) To stretch the foreshortened terrain into a square, select the
terrain and click the small A near the lower right corner of the
terrain. The Object Attributes dialog then appears (Figure 4, right).
Enter a Z value approximately twice that of the X. Use the square Bryce
document window as a visual reference for determining when the terrain
has become nearly square. It doesn’t have to be perfect.
Figure 4 (left) The Object
Attributes palette in Bryce is
accessed by clicking the small “A” at the lower right corner of a
selected wireframe terrain. (right) Entering a Z value about twice as
large as that of the X value elongates the terrain (in the direction
shown by the arrows) to a nearly square shape.
9) Render the scene and save the image in Photoshop format.
1) In Photoshop, open the image of the perspective terrain you just
rendered in Bryce.
2) Go to Image/Canvas Size and increase the canvas size by 120% on all sides. The extra space will give you maneuvering room later when you transform the image.
3) You will need two layers in Photoshop. Place the rendered Bryce terrain on the top layer. Lessen the opacity and/or change the blending mode of the top layer in order to see through to the layer below.
4) On the bottom layer place the original square map before it was rendered in perspective in Bryce. If this is unavailable, any square filled with a flat color will do (see Figure 3, left). Size the square as close as possible to that of the Bryce image above.
5) On the top layer, use the Rectangular Marquis Tool to draw a selection over the entire perspective terrain. Include a little extra space on all four sides.
6) Select Edit/Free Transform from the top drop menu and adjust the size and shape of the perspective Bryce scene to register with the square below. Because the top and bottom edges of the Bryce terrain are crenellated by topography, the straight left and right sides of the Bryce terrain are a better alignment guide.
Tip: Holding down the Command key (Mac)/ Control key (PC) and click-dragging the any of the corners of the transformation box permits non-rectilinear distortions to the image.
7) Double click inside the transformation box to apply the
transformation. The transformed Bryce terrain should now exhibit the
planimetric characteristics and 3D topography.
Perspective depth: Unlike panoramas, on 3D planimetric maps adding atmospheric haze or diminishing the width of linework in background areas is inappropriate because foreground and background areas don’t exist on these maps.
Aerial perspective effect: Valley haze used to differentiate lowland from highland areas is appropriate to show on 3D planimetric maps. A height mask rendered separately in Bryce is essential for applying this effect. To use height mask you must transform it to exactly the same planimetric shape as the 3D relief. You do this by recording the transformation applied to the 3D relief as a Photoshop Action and replaying it to transform the height mask.
Lighting: Standard northwest illumination used with traditional shaded relief does not apply to 3D planimetric relief because it places deep shadows on slopes facing the viewer. Lighting on 3D planimetric relief should originate from the lower left or right similar to the lighting used on panoramas and depending on how the topography trends. If everything else is equal, use lower left illumination because it is closer to the cartographic standard.
Mountains needed: 3D planimetric relief works best for maps containing high relative relief. On gentler terrain 3D relief looks too similar to shaded relief, which results in confusion.
Sharpening: If background (top) areas look fuzzy after applying Photoshop transformations, correct it by selectively applying the Unsharp Mask filter. I prefer to create two layers in Photoshop with copies of the 3D relief on each. I then apply an appropriate amount of Unsharp Mask to the relief on the bottom layer. Finally, on the top layer I add a layer mask and fill it with a linear gradient (applied from bottom to top), which allows sharpened terrain at the top to show through.
Resolution bumping: Vertical exaggeration applied to
small-scale elevation data causes tall solitary peaks on 3D relief to
spike upwards in an unsightly manner. Using a DEM manipulation
technique in Photoshop called resolution bumping before rendering the
DEM in Bryce lessens this problem. To learn more about the resolution
bumping technique click here.
Figure 5. Resolution bumping allows the application of
substantial vertical exaggeration to 3D planimetric relief. Without the
application of resolution bumping on this map Mt. Ararat would appear
as a tall spire.
Linework: Creating a map with 3D planimetric relief map takes more time than making one with traditional shaded relief. Dealing with linework contributes greatly to the additional time. Linework on 3D planimetric maps interacts with topography in the same manner as on panoramas: it goes up and down. For example, a political boundary following the crest of a mountain range would rise and fall with the mountains and occasionally disappear into deep valleys. To accurately plot lines requires draping lines on the 3D topography in Bryce and creating a separate render with only lines for compositing in Photoshop afterwards. A possible exception to this approach is the graticule that could overlay the map without interacting with topography.
Getting creative: The techniques covered so far yield 3D
relief that is accurate and looks competent, but lacks artistic style.
To give your relief a painterly look experiment with the artistic
filters in Photoshop in combination with one another (Figure 6). If the
effect of a particular filter appears excessive even at the lowest
settings possible, using the Fade command (Edit/Fade) after applying
the filter gives finer control over how it looks compared to the