Transforming projected coordinate system using QGIS?

Question

I have two raster datasets, they have different projected coordinate systems; one in WGS_84_UTM_Zone_N34, another in Hungarian_1972_EOV, they overlap each other perfectly if I open them in QGIS.

I would like to transform the coordinate system of the first raster into the second.

I tried Project Raster tool in Data Management toolbox (ArcGIS), it converted the first raster into Hungarian_1972_EOV, but it doesn't overlap with the second raster perfectly (There is a shift between two raster datasets fo about 10-15 meters).

Can anybody help me to find out what is the problem?

Answer 1

EPSG:23700 HD72 / EOV is defined inside QGIS with this projection string:

+proj=somerc +lat_0=47.14439372222222 +lon_0=19.04857177777778 +k_0=0.99993 +x_0=650000 +y_0=200000 +ellps=GRS67 +towgs84=52.17,-71.82,-14.9,0,0,0,0 +units=m +no_defs

As you can see, there is a Datum shift from HD72 to WGS84 included in the definition.

ARCGIS handles projections differently, and by default (from the .prj file) no datum shift is applied. You have to do it manually to get the same correct results as QGIS does, either on-the-fly or explicitely reprojecting.

Answer 2

You can do this in qgis itself, refer to 7.14 Follow Along: Saving a Dataset to Another CRS

All of these instructions may not be pertinent, this is from the teach-by-example guide Specifically in the example they transform to WGS 84/UTM (steps 8 and 9), and you want to go to Hungarian_1972_EOV. You may also want to change the Encoding (depending on your use case).

1. Select Save As... in the menu that appears. You will be shown the Save vector layer as... dialog.
2. Click on the Browse button next to the Save as field.
3. Navigate to exercise_data/ and specify the name of the new layer as buildings_reprojected.shp.
4. Leave the Encoding unchanged.
5. Change the value of the Layer CRS dropdown to Selected CRS.
6. Click the Browse button beneath the dropdown.
7. The CRS Selector dialog will now appear.
8. In its Filter field, search for 34S.
9. Choose WGS 84 / UTM zone 34S from the list.
10. Leave the Symbology export unchanged.