Converting Raster Data to Local Coordinate Systems with Scale Factor

Often clients require deliverables in local coordinate systems. True View EVO has the full ability to scale and transform point clouds to a local coordinate system. We are actively developing a built-in GUI method to scale and transform raster data, typically orthomosaics. Temporarily we have a workflow using a batch script that will perform this task for you. This will need to be performed on a computer with an actively licensed version of EVO.

Obtain a copy of the following files from GeoCue support and place these three files into the same folder. The location does not matter they just need to be together

ApplyAffineTransform2Raster.txt (rename to .bat)

Jsonextractor.txt (rename to .bat)

ExportENasCSV.xml

The batch file will receive the scale factor values from a exported copy of the point cloud task you use to scale your LAS point cloud. First, setup a point cloud task with the task type for Affine Transform. Use the scale and transform values as needed to convert to your local coordinate system. Ensure that Maintain Source File Structure to keep your LAS data tiled and that Geotag as Local SRS is checked. Run the PCT and then verify you point cloud is correctly placed on the local coordinate system using check points or a visual inspection. Change your export path to <LP360_PROJECT_PATH>\LocalSRS\ verbatim, turn off Maintain Source File Structure and export a copy of the point cloud task in the point cloud manager in xml format and note its location for the next step. When exporting ensure that the your Affine Transform PCT is the only checked in the Point Cloud Task Manager.

True View EVO needs to be closed during the batch script execution. You will need to enter a command line entry detailed below:

  1. Open a command line prompt (Window Key and type CMD and Enter)
  2. Drag and drop your ApplyAffineTransform2Raster.bat into the console window and press spacebar
  3. Drag and drop your raster file and and press spacebar
  4. Drag and drop your AffinePCT.xml file and press space
  5. If your project is in survey feet type sf, or for international feet ft, or for meters m

Your command line entry should look like this, double check your syntax and hit enter to execute.

Example:

“C:\Ortho_Scale_Tool\ApplyAffineTransform2Raster.bat” “E:\Test_Project\Photo_Package\Metashape\Photo_Package_20210802T1112\Photo_Package_20210802T1112_ortho.tif” “E:\Test_Project\Photo_Package\Metashape\Photo_Package_20210802T1112\Affine_Transform_PCT.xml” sf

The local SRS orthomosaic will be generated in the same folder as the input and be called the same name, but with “_localsrs_[m or sf or ft]” appended to it.

Example:

Photo_Package_20210802T1112_ortho_localsrs_sf.tif

Photo_Package_20210802T1112_ortho_localsrs_sf.tfw

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