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 process a merge polygon that spreads 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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