TerraMatch Adjusted Working Segments

Problem:

In GeoCue, when populating another layer of working segments, generating LIDAR orthos, or LIDARgrammetry stereo pairs from a layer, where that source layer has been adjusted using TerraMatch after the population of those source working segments, one might notice some slivers of missing data that follow the boundaries of the source working segments. The “gap” may vary in differing circumstances depending on how much of a horizontal adjustment was made to the data by the TerraMatch correction. Where it may not exist at all to where it could be quite sizable.

Probable Resolution #1:

After applying a TerraMatch derived correction to a dataset, the data is typically shifted by some amount. That amount may be smaller than the NPS, or could be quite large. This can lead to a scenario where the extents of the working segment entity no longer correspond with the data in the associated LAS file. The result is the gap along the geometry extents as the entity geometry is used by GeoCue to determine if the source LAS file intersects with the destination entity, whether that is an ortho image to be generated or another working segment that is to be populated. And, since the LAS data in the source layer does not align with the entity, then there will be times where some of the neighboring tiles containing the necessary data do not get selected as sources to populate the destination working segment.

To resolve the issue is a two step process:

  1. Change graphic type on the source working segments to convex hull, so they align with the data contained therein.
  2. Populate the destination working segments, or generate the imagery, as the case may be, while the source entities are displayed using the convex hull.
  3. Feel free to change the entities back to original graphic after the convex hulls are no longer required.

This process allows GeoCue to correctly see the extents of the source LAS files to properly determine which working segments are needed to populate and fill in the gaps that you’re seeing in the destination working segments. Anytime the user creates a significant horizontal shift in the data using TMatch workflows, etc., you need to use the workflow of changing the graphic for the source layer working segment entities before: populating a destination layer from it, or generating orthos, etc.

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