Shablab Posted February 15, 2019 Share Posted February 15, 2019 I am looking for a Lisp that will ask for a point on a surface to be selected and from there it will draw a polyline and go uphill until it reaches a high point. For those unfamiliar, the water drop does this but the starting point is the high point. I need to be able to use this command anywhere on the surface and that's why the catchment tool doesn't work in some circumstances. As of now I have been just clicking around on the surface using waterdrop tool until a point hits. Quote Link to comment Share on other sites More sharing options...
tombu Posted February 16, 2019 Share Posted February 16, 2019 That would make creating drainage areas easy! Hope someone has a simple trick they can share. Quote Link to comment Share on other sites More sharing options...
BIGAL Posted February 17, 2019 Share Posted February 17, 2019 Pretty sure solution exists here but it was years ago, may take a while to find. Civ3d has an in built display option and shows a direction arrow for triangles. Quote Link to comment Share on other sites More sharing options...
BIGAL Posted February 18, 2019 Share Posted February 18, 2019 Learn something new everyday Quote Link to comment Share on other sites More sharing options...
Commandobill Posted February 19, 2019 Share Posted February 19, 2019 BIGAL, I think the OP wants that solution but in reverse. Civil 3D does the water drop from high point to low point. Quote Link to comment Share on other sites More sharing options...
BIGAL Posted February 19, 2019 Share Posted February 19, 2019 (edited) Need to search for the other solution I think thats what it did, uses 3dfaces. look at the top webpage http://www.gilesdarling.me.uk/lisp/calcslopefrom3pts.pdf Edited February 19, 2019 by BIGAL Quote Link to comment Share on other sites More sharing options...
Shablab Posted February 20, 2019 Author Share Posted February 20, 2019 On 2/19/2019 at 9:36 AM, Commandobill said: BIGAL, I think the OP wants that solution but in reverse. Civil 3D does the water drop from high point to low point. That's correct, the command waterdrop already exists in Civil 3D but it is only from high to low point. The waterdrop tool does use 3dfaces along the surface I just need the reverse direction as the existing command you can only use from a highpoint. Quote Link to comment Share on other sites More sharing options...
BIGAL Posted February 21, 2019 Share Posted February 21, 2019 I googled and found the post above also found linked to that post a start for a solution, it shows the slope grade and direction with an arrow replace the arrow with a line then work out next intersect point and keep going. I am still sure a solution exists do a search for "slope direction". Quote Link to comment Share on other sites More sharing options...
kirby Posted February 22, 2019 Share Posted February 22, 2019 Some other tools can do this, but nothing built into C3D. Certainly possible to develop something based on a TIN and 3dface normal (projected onto XY axis as direction of maximum slope). Search for David Tarboten's 'Taudem' software, which uses gridded data to aggregate flow contribution. This describes some of the issues, including: filling of depressions (an issue in Canadian Prairie 'pothole' country, where I live) dealing with flat surface areas (ditto re prairies) Generate a stream path after 'n' grid cells (or 'burn in' / utilize streamlines from another source) maximum size for generated catchments An older version of Taudem (called Tardem) works on the command line, and has lent itself well to calling from AutoCAD and using CAD data to prepare input and process output. Nowdays we use a couple of tools built into Global Mapper software, including 'Find Ridgelines' and 'Generate Watershed' that use terrain model data (eg. Bare earth LiDAR or ERSI Arc Grid, or grid based on a TIN). Specialty drainage modeling software also may have this built in (PCSWMM expert system for US EPA Stormwater Management Model has this, very handy for quick and dirty natural drainage model development). Quote Link to comment Share on other sites More sharing options...
JaysonE Posted August 30, 2019 Share Posted August 30, 2019 I posted a solution to this post in the Autodesk forums. https://forums.autodesk.com/t5/civil-3d-forum/reverse-waterdrop/m-p/8997728/highlight/false#M405845 It involves inverting (mirroring) the surface to trick the Water Drop tool to draw from low to high. Quote Link to comment Share on other sites More sharing options...
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