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LAS format and processing DTMs from tins and local binning Arrowsmith.

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Presentation on theme: "LAS format and processing DTMs from tins and local binning Arrowsmith."— Presentation transcript:

1 LAS format and processing DTMs from tins and local binning Arrowsmith

2 LAS files: industry standard format

3 Example of EarthScope Northern California LiDAR data from Mill Gulch along the San Andreas Fault (NCALM data processed at and downloaded from OpenTopography)

4

5 Grids in ArcMap for context

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7 LASTOOLS

8 Install LASTOOLS somewhere like C:

9 Install LASTOOLS arc toolbar

10 las2shp using LASTOOLS toolbar

11 Need to define the projection for the shapefile

12

13 Need to make a las dataset in Arc

14 LAS dataset in ArcMap

15 LAS file in ArcMap

16 LAS file in ArcScene

17 Generating DEMs from LIDAR LIDAR points raster DEM resampling interpolatingtriangulating temporary TIN i j Isenburg, et al., 2006

18 Inverse Distance Weighting ( IDW ) Natural Neighbors Kriging Splines TIN – linear – quintic … Interpolation Methods Isenburg, et al., 2006

19 Streaming TIN output output final DEM to disk DEM Generation via TIN Streaming small buffer in main memory Streaming Computation of Delaunay Triangulation read points from disk Immediate Rasterization of Streaming TIN store elevation rasters to temporary files (grouped by rows) Isenburg, et al., 2006

20 Example Result 500,141,313 Points 11 GB ( binary, xyz, doubles ) on a household laptop with two harddisks 50,394 × 30,500 DEM 3 GB ( binary, BIL, 16 bit, 20 ft ) raster DEM LIDAR points in 67 minutes 64 MB of main memory 270 MB temporary disk space Isenburg, et al., 2006

21 blast2dem

22 BLAST2DEM DEM

23 Strip: …it's a licensing issue. to get around it (for academic or personal use) you can simply use lastile to make it small enough and then run blast2dem on smaller tiles and then recomposite with GDAL. Martin Isenburg

24 Windows version: points2grid.html

25 An Efficient Implementation of a Local Binning Algorithm for Digital Elevation Model Generation of LiDAR/ALSM Dataset (Kim, et al., 2006)

26 Need comma delimited file for P2G

27

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29 1 m local binning dem

30 1 m radius shot density

31

32 Ground returns only (TIN)

33 Ground returns only (1 m radius IDW)

34 Points over bare earth surface


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