TUFLOW Message 2934

TUFLOW Message
WARNING 2934 - At least one merge polygon vertex is outside quadtree sub-domain. Current nesting level = n

Alternate Message
CHECK 2934 - At least one merge polygon vertex is located inside quadtree cell(s) from different nesting level. Processing nesting level = n

Message Type
WARNING
CHECK

Description
Issues can occur in the TIN process when 2d_zsh polygons intersect with multiple quadtree levels.

Suggestions
Check by reviewing the _zsh_zpt and DEM_Z check files that the appropriate topography modifications have been applied. If they haven't, options include:

• extend the 2d_qnl to cover the entire 2d_zsh,
• create a TIN using QGIS or SMS and read the TIN into TUFLOW directly (using the TGC command 'Read TIN Zpts =='),
• snap 2d_zsh elevation points to every 2d_zsh polygon vertex, or
• use the "NO MERGE" option and supply elevations as needed.

In TUFLOW Build 2025.2.0, updates were made to the processing of merge polygons that spread across multiple Quadtree domains (e.g. nest levels). During Quadtree pre-processing, TUFLOW constructs a Quadtree mesh for each nest level, but only updates the ZC/ZU/ZV/ZH elevations in the final Quadtree mesh. For the “hidden” Quadtree mesh illustrated in the image below, the elevations were not being updated. A fix has been made to update both the “hidden” and “active” Quadtree meshes. After this change, a merge polygon that spreads across multiple Quadtree domains can use the elevations from the “hidden” ZC/ZU/ZV/ZH points for merging elevations. This reduces the risk of applying unexpected elevation at the tin vertices of a merge polygon. Reviewing the final elevations with the _zsh_zpt and DEM_Z check files is still recommended, given users are unable to see the elevations used for merging within the hidden mesh areas.

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