CompuServe Thread

GIFDXF does not convert b/w GIF images into vector files the way you're thinking. It converts 8 bit GIF files (maybe lesser color too) into DXF polyface mesh files. It does so by converting each pixel into a point and then connecting all the points into faces. The altitude at each point is determined by the intensity of each pixel, or it's index (color 0 = altitude 0, color 1 = altitude 1 etc). A 100×100 pixel GIF image will result in a 10,000 point object with 20,000 faces — even if it is completely flat. You can force the program to sub-sample the source image to create smaller, less detailed DXF objects. GIFDXF is limited to 100×100 point DXF objects, I think, or maybe it's 128×128. Vistapro is a landscape rendering program — a 3D renderer specifically for rendering landscapes. You can easily add rivers, lakes, trees, clouds, change colors etc. It uses many fractal algorithms to add detail to "lo-res" landscapes. It can currently handle landscapes as large as 1026×1026 points, and can render images as large as 4096×4096 pixels in 24 bit color. Typical renderings from Vistapro contain 1 to 10 million 3D polygons. The largest I've made so far was 150 million and it took 10 hours to generate. David Taffet mentioned using GIFDXF with Vistapro files because Vistapro can export it's landscapes as PCX images in which altititude is encoded as color. You can convert the PCX files to GIF files, then use GIFDXF to convert the GIF to a DXF. The technique works reasonably well — but Vistapro can generate nicer looking landscapes than 3DS. Hence he recommends using the DXF landscape as a guide for placing foreground 3DS objects, or as a matte, and then using the Vistapro image as a background in 3DS. A new release of Vistapro (3.1) will be available soon that can directly save it's landscapes as DXF objects. It can also save the texture maps for use with the DXF object in 3DS. It will have a utility program that will convert 3DS VUE files (animation scripts) into Vistapro's format. This makes it much easier to generate a series of background images that are synch'd to a 3DS animation. Vistapro will automatically break large landscapes into smaller DXF objects since there is a 64K point and face limit in any single DXF object. Be forewarned, a "huge" vistapro landscape (1026×1026 points) will create a 250MB DXF file at "full" detail. Vistapro uses it's own data format for landscapes, but there are free utilities that can convert USGS ASCII DEM, ASCII Y, ASCII X,Y,Z, and some vector formats into it's format. There is a usable demo (no load and save, but most other functions enabled) in VRLI's section of GraphAVendor (GO VRLI).

>we are talking about a b/w pcx/gif, as in a 2 bit rastor scanned< Not so, sir. These are 8-bit files where the color graduations (converted to greyscale) are interpreted by the GIFDXF converter as differences in elevation. VistaPro is a commercially available fractal landscape generator that can output 8-bit or 24-bit landscapes and fly-throughs thereof. (It creates the landscapes in 3D.) It also has an option to save the landscape, as seen from above, as a PCX, which we then convert to GIF, then to DXF then into 3DS. It will output very large resolutions, independant of your screen, as well. Talk to John Hinkley, here on the forum. He is the renowned programmer of the VistaPro program and can give much better descriptions of its capabilities. <g>