1

I have just received a large amount of ASCII DEM files. In total 564 Files each containing 40,000 point data (22.560,000 Points). I would like to convert this into a point cloud with a view to interpolating to raster for analysis and cartographic output. I have both ArcGIS Advanced and FME 2014 to work with. I did this before a few years ago and had problems importing into Excel due to restrictions on the amount of rows excel can read/write. Does anyone do this kind of work regularly and could advise me on suitable workflows to produce raster data from these files including the prep-work to create point cloud data, and also the interpolation process to create realistic and accurate raster data.

The data format is one point per line...unfortunately each file has the file name written on line 1, and there are other data written in the columns such as a code for the data source as well as slope (gon) and aspect (gon).

2

In FME it would depend on the precise source format.

If - as someone has suggested in the comments - the ASCII lidar is simply a series of x,y,z values then use the Point Cloud XYZ Reader, and a Writer such as LAS (or whatever point cloud format you want).

Otherwise using a raster Reader (Esri ASCII Grid format?) and then use the PointCloudCombiner transformer. From the help:

PointCloudCombiner is often used to accumulate multiple point clouds into a single point cloud feature, but can also convert other geometries into point clouds and merge them.

Rasters will be converted to point clouds as follows:

  • The x and y components will be created from the columns and rows.
  • The first selected numeric band will become the z component.
  • The first selected bands with red/green/blue/gray interpretations will become the color_red/color_green/color_blue components.
  • Additional selected bands will also be preserved. If the band has a name, the component name will be the band name. If the band has no name, the component name will be bandN, where N is the band index.
0

Depending on the source of your DEM files you may be able to use the DEM to Raster GP tool. This tool is specifically for importing USGS DEMs. Otherwise, as Jakub mentioned above, try ASCII to Raster.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.