Hans van der Maarel, frax, Alpine Mapping Guild, BEAVER, DaveB,
Many thanks for your comments and encouragement. I want to upload a clear image, but failed, due to the 500k limit of uploaded file. I have to process the files and reduce them as little as i can. Wish you can see the detailed part then.
the terrain file is 100m res. of grid (arcinfo version) resulting from 1:250,000 contour file. But it's too detailed for such a large area, which is equal to 6 california or so. In erdas, I have to set down the show detail, samiliarly decreaseing the resolution of the dem.
The satellite is ETM of 30m res. The original ETM is merged from band 7, 4, and 2, so it's false color. After convert it into Tif version, I modify it near to natural color, according as the physiognomy zone. For example, the Caidamu Basic is a very dry basin, with some fan-like oasises in the end of river. I made the color of this area like dry. In addition, the northeast of the map is the verge of west Loess Plateau. Originally, the ETM image shows green. But to approach to the landscape we are familiar with, I modify it near to yellow. Then I attached projection to the tif file, overlayed on it other vertor file, like river, city, province line, in arcmap. Output them respectly, overlay them in photoshop and modify them further. In the end, drape it on the terrain file in erdas. Set light, angle, show detail, and so on. In the end, output it and adjust it further in ps. I add city and river name in illustrator and large area of texts in pagermaker, because illustrator cannot deal with interpunction of Chinese characters correctly.
Because the area is too large, I make the angle near to flat. If incline a big angle, some mountain area would show broken-up. To project the mountain effect, I have to exagerat the vertical direction greatly. It looks really weird, as Alpine said.
1. the ETM (band742) is false color. I don't know how to adjust it to real natural color. I know terracolor can do it. see http://www.terracolor.net/
But terracolor's images are so valuabe that I cannot afford them. Do you know how to adjust to terracolor-like effect?
2. Compared with some 3d software, Erdas doesn't have advantages in rendering and lighting effect. You can see the mountain shadow is very dark. Modifying it later is rather a great job. But in my view, erdas has two merits: having very fast speed in processing very large raster data; adjusting the show resolution detail expediently.
Bryce is great in processing rendering and lighting effect. But it's slow and adjust the dem detail. As usual, I bump it in ps and test the effect in bryce. A good news comes that Bryce can load large area of dem, just dividing dem into several square tiles and overlaying corresponding images. I'm trying it. I wish erdas can combine the merits of bryce, or just the reverse.