Bug report #9070
+towgs84 wrongly ignored when OTF reprojection is on and project CRS is WGS84 Pseudo-Mercator (EPGS: 3857)
| Status: | Closed | ||
|---|---|---|---|
| Priority: | Severe/Regression | ||
| Assignee: |  Marco Hugentobler | ||
| Category: | Projection Support | ||
| Affected QGIS version: | master | Regression?: | No |
| Operating System: | all | Easy fix?: | No |
| Pull Request or Patch supplied: | No | Resolution: | |
| Crashes QGIS or corrupts data: | No | Copied to github as #: | 17716 |
Description
Issue seems to have appeared following the (cool) datum transformation commits. Steps to reproduce:
1. Create a new project
2. Load the roads_partial-indian1960_48n shapefile
3. Open the project property, set OTF reprojection to on and the project CRS to EPSG:3857
4. Load the roads_partial-wgs84 shapefile
5. You'll notice a 500m shift between the two layers, when those two layers should be identically placed on top of each other
The 500m shift is what happens when the +towgs84 parameter is not applied (I learned that from an much older bug :) ). The reprojection issue here won't happen if you repeat the above steps but set the project projection to WGS84.
This is a pretty impactful issue here as it affects @the openlayers plugin (which sets the projection to EPGS:3857). Confirmed over here on two linux machines and windows.
Associated revisions
History
#1
Updated by Marco Hugentobler about 11 years ago
- Assignee set to Marco Hugentobler
#2
Updated by Marco Hugentobler about 11 years ago
Maybe a problem with the null grid parameter that is removed now. Looking into that problem on Monday.
Do know which of the two layers is misplaced?
#3
Updated by Mathieu Pellerin - nIRV about 11 years ago
- Target version changed from Version 2.0.0 to Future Release - High Priority
Marco,
I think the indian 1960 48n layer is the one being misplaced/misprojected, based on fact that if you load that shapefile, then add a openlayers' google satellite imagery layer, you'll notice the vector layer is clearly 500m to the southeast of where it should be. Steps to reproduce that:
0. Download and activate the openlayers plugin
1. Create a new project
2. Load the roads_partial-indian1960_48n shapefile
3. Add a google satellite imagery layer via openlayers (it'll activate OTF reprojection and change CRS to EPGS:3857
(If the google layer shows the whole world, just zoom in and out once)
4. You'll notice a 500m shift between the two layers, when the visible roads on the google layer should match the vector layer
#4
Updated by Marco Hugentobler about 11 years ago
- Status changed from Open to Closed
Fixed in changeset 51006cea1f2959b0e659a8ee07577632dc3c2753.
#5
Updated by Mathieu Pellerin - nIRV about 11 years ago
Marco, thanks, glad this was uncovered and fixed early on :)