The analysis fails for high-resolution elevation data:

The analysis is based on the Computational Geometry Algorithms Library (CGAL) and is thereby limited to the resolution of data that can be triangulated and analyzed in memory. There is no specific size where the analysis will fail. Rather, it depends upon a variety of factors, such as the amount of Random-Access Memory (RAM) on the machine, the memory usage and fragmentation from other applications, and triangle decimation from the collapsing of nodes. There are three things to try if the analysis fails:

1. Increase the RAM available for the tool by doing any/all of the following:
   • Closing other applications.
   • Adding physical RAM to your machine.
   • Running it on a machine with more RAM.
2. Limit the extent of the elevation data either by clipping the data or by setting a smaller geoprocessing extent to your area of interest.
3. Reduce the resolution of the elevation data by increasing the cell size in the raster analysis geoprocessing environment settings.

The analysis fails for one item or a few items only:

This will appear as an ‘invalid feature’ warning, listed in the GP tool results, such as:
WARNING 050086: Invalid feature ignored in QA_MinZone, OID: 4.
This is due to a non-closed source shape which will be specified by OID in the GP results. All efforts have been made to limit this from happening in the GP model, but you still might see it. To help you identify the failures, the GP model also creates QA_MinZone.shp and QA_MaxZone.shp. The features that have a value of IsClosed = No are the failures.

Keeping intermediate data in shapefile format will combat this issue. When converting any GIS feature into the geodatabase, an underlying integer grid (at your defined precision) is used to reduce data storage size, and, for highly detailed multipatches, this grid might cause triangle decimation. A single decimated (collapsed or destroyed) triangle is enough to cause the IsClosed property of a 3D object to fail.

Development work is continuing to reduce these cases further. However, a significant part of the underlying code belongs in the embedded CGAL library and is therefore not directly under Esri development control. There are three things to try if the analysis fails for individual features:

1. Increase the RAM available for the tool by doing any/all of the following:
   1. closing other applications.
   2. adding physical RAM to your machine.
   3. running it on a machine with more RAM.
2. Limit the extent of the elevation data (either by clipping the data, or by setting a smaller geoprocessing extent to your Area of Interest).
3. Reduce the resolution of the elevation data by increasing the cell size in the raster analysis geoprocessing environment settings.