Misalignment of Coordinate system using TopSar split

[blueyeti1881]

Implementing Topsar split using default settings appears to change the georeference. I applied topsar split to and used the same WKT to draw a polygon on before and after image, but the position of polygon is on left side on image after implementing the topsar split.

[diana_harosa]

@djagula can you have a look? Thanks

[jun_lu]

The geocoding for the S-1 IW SLC product before split is created using the corner points of the IW1 and IW3 swathes and is not accurate. The geocoding for the split product is generated using the tie point grid of the swath and is accurate. Therefore, we should avoid using the geocoding of the full product and should use the split product instead.

[blueyeti1881]

@jun_lu Thank you for information. Here is the problem i’m facing and no idea how to avoid such errors. i couldn’t upload file as it was more then 4 MB, so could you please suggest what i’m doing wrong and how to solve this error.
https://youtu.be/fXi_zWH9EwQ

[blueyeti1881]

I’m lost here. I used the real coordinates lat_max/lat_min/lon_max/lon_min by drawing box from (https://boundingbox.klokantech.com) and when i used this in the product without split, it covers my AOI and it appears same as in the website. but when i used the same coordinates to drawy polygon over splitted products, it doesn’t cover my AOI as it is shown in website i used to get coordiantes. so splitted produces appears to have not accurate if i compare real website coordiantes and polygon of splitted products.

[jun_lu]

Below is the test we have done with the following S-1 product:
S1B_IW_SLC__1SDV_20200815T173048_20200815T173116_022937_02B897_F7CF

1. First we created a bounding box for Saint-Etienne, France using the Bounding Box Tool:
   
   
2. Second we copied the polygon in WKT format: POLYGON((4.380122 45.445096, 4.415484 45.445096, 4.415484 45.420762, 4.380122 45.420762, 4.380122 45.445096))
3. Third we created a geometry in IW1 of the full S-1 product using "Geometry from WKT):
   
   
4. Finally we created a geometry in the split IW1 of the S-1 product:
   
   
   
   Here we can see that the geometry in the split image is more accurate than that in the full image.