I am using LIDAR ASC files to generate a large storm water catchment area which I would like to then combine with some survey work including river bathymetry to actually combine the data to have one complete surface file so we can complete a flooding model of our at risk coastal foreshore communities. Our survey work is in A3D and our flood modelling software (XPSWMM) prefers ASC file types, my problem is exporting from AutoCAD 3D and getting the file into a ASC file type.

Once I get all the files into an ASC format I have no issues about combining the files together. I just can't figure out how to get from A3D to asc file type! I am just getting frustrated now! I know it should be simple, we are using two leading software packages and there seems to be no easy transfer of data.

Software I have at my disposal to achieve this is; A3D, FME (limited experience), MapInfo with engaged 3D extension, XPSWMM.

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    This is how I do it using ArcGis, certainly similar things can be done in mapinfo. Triangles to 3d points, delete duplicate, create TIn from points, tin to raster, raster to ascii grid. With some python can be done differently by deriving equation of triangles z (x,y) and interpolating points. Good luck – FelixIP Nov 20 '15 at 5:01
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    Is an asc file an Esri Ascii Grid? If so, FME should be able to convert from AutoCAD to that format fairly easily. Otherwise, is it a simple ascii format (like x,y,z values)? – Mark Ireland Nov 20 '15 at 17:24
  • I have created and exported the 3D points generated by the TIN from autocad, exported to a CSV. Imported into FME, used the Vertex Creator, added the LIDAR points used the Surface Modeller and added the breaklines, I am just trying to write to any of these formats *.ASC, LandXML, XYZ file. But the translation falls over at this point (if i use the inspector the workflow works fine, its just writing to a file). I am very limited in FME experiance. – Pat Nov 27 '15 at 2:07
  • I could write to Esri Ascii Grid files too. – Pat Nov 27 '15 at 3:01

Probably not the most efficient workflow, but it works.

From the detail survey in AutoCAD3D, I exported the 3D points generated from the Triangles into an Excel Spreadsheet (https://civil3dplus.wordpress.com/2010/01/05/extracting-points-from-a-surface/). I also exported the breaklines, and extents of survey (for clipping the LIDAR data that is within the survey area) and the extents for the modelling area. Imported this information into FME. I put the CSV through the vertex creator transformer to create the 3D points and then directly into the Surface Modeller.

I clipped our combined LIDAR tiles into a smaller area and imported into FME as an ERS file and used the rasterCellcoercer to extract the Z values, put this into a SurfaceModeller and outputted as Vertex points, and then Clipped this data with the extents of modelling area, and then another clipper to exclude the survey area from the LIDAR information. Placed this workflow into the Surface Modeller with the CSV point file. I then outputted the DEMpoints to a RasterDEMGenerator transformer and added my breaklines. For some reason i needed to clip the modelling extents again (i guess i could just move my first clipper) and then outputted as an Esri Ascii Grid. As I have mentioned probably not efficient but it works for me and I have only been using FME for maybe 4 months and hadn't gotten to this type of scenario yet. I hope this helps anyone with a similar situation.

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