Opened 3 weeks ago
Last modified 3 weeks ago
#5735 new defect
ST_TRANSFORM uses Helmert transformation instead of NTV2 grid (SRID's : 3812 <->31370)
| Reported by: | martinvdb | Owned by: | rouault |
|---|---|---|---|
| Priority: | medium | Milestone: | PostGIS 3.4.3 |
| Component: | postgis | Version: | 3.4.x |
| Keywords: | ST_TRANSFORM Belgium NTV2 | Cc: | martinvdb |
Description
When I want to transform coordinates of objects stored in Lambert72 (SRID : 31370) to Lambert2008 SRID : 3812), the ST_TRANSFORM function uses the Helmert transformation. However there is a more precise trasformation using the NTV2 grid. I managed to create that transformation using the new ST_TRANSFORMPIPELINE. However, when I try this transformation in PROJ, the default transformation is the most precise one using the NTV2 grid. My questions are :
Why ST_TRANSFORM still use this old unprecise method? Can I change the behavior of the ST_TRANSFORM to perform the transformation using the NTV2 grid?
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@martinvdb Can you post an example (using for example just a point) of the ST_Transform() invokation you tried, what you got and what you expected as result?