![]() ![]() ![]() The red are from TIF DEM, 2-ft minor, 10-ft major. TIN triangulation was turned off, contours were left on.īelow are two sets of contours, each generated from a raster (TIF and ASC). There's another one hidden and underneath. Lower left corner of both TINs where one used a TIF DEM and the other used ASC DEM.īelow are all surfaces: two raster surfaces and two TINs. Their surface contours overlapped as well. They each verified the geospatial accuracy of the another. Remember, both rasters used FDO connections and overlapped. Why? Because neither TIN matched up with either raster. So which TIN was right? The one created with TIF or the one created with ASC? Answer: neither, IMHO. When I compared the two, they were off: 5 feet in x-direction and 5 feet in y-direction. First TIN used the TIF as a definition and the other used the ASC. I then created two separate TIN surfaces using the same DEMs. Exactly (pause and breathe) on top of one another. The result: surface contours were also on top of one another. To test accuracy, I generated surface contours from each raster. When I used Map, both rasters came in looking like they were on top of one another. First way used the DEM as a definition to create a surface, and second kept the DEM as a raster entity and used Map 3Ds FDO connection. To demonstrate, I've brought in both of your DEMs into modelspace using two different ways. Just because you've created a surface doesn't necessarily mean it's in the right spot. Regardless of interpolation, algorithms, Civil 3D this, Civil 3D that, system variables, or AutoLISPs, if Civil isn't interpreting your DEM location correctly, then your TIN surface will be off. (Yes, a DEM is a map, it's a map of pixels.) Before using DEMs, whether ASCs or TIFs, to create a surface, they must be geospatially accurate when imported. Although C3D is excellent at road design, installing underground structure and estimating volumes, it is not good at mapping, at least not as good as Map 3D. That method, however popular and well-accepted, can give erroneous results. By workflow I mean, using a DEM to create a surface which uses a raster as a definition. Command line tools (dwg2pdf, dwg2svg, dwg2bmp, etc.)Ĭlick here for a complete list of features.Unfortunately your workflow is not ideal.Very complete and extremely powerful ECMAScript (JavaScript) scripting interface.Various powerful entity selection tools.Construction and modification of points, lines, arcs, circles, ellipses, splines, polylines, texts, dimensions, hatches, fills, raster images.You can download QCAD today for free! Main Features You don't need any CAD experience to get started with QCAD immediately. QCAD is an easy to use but powerful 2D CAD system for everyone. But what people notice most often about QCAD is its intuitive user interface. QCAD was designed with modularity, extensibility and portability in mind. The source code of QCAD is released under the GPL version 3 (GPLv3), a popular Open Source license. ![]() With QCAD you can create technical drawings such as plans for buildings, interiors, mechanical parts or schematics and diagrams. QCAD is a free, open source application for computer aided drafting (CAD) in two dimensions (2D). ![]()
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