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How to use projection information in WKT form to define projection for a raster?

FiveO

I have a raster file with Unknown Coordinate System and a WKT-file that has the CS information. How do it connect those two in ArcGIS Pro? The Define Projection tool gives me an option to create a new coordinate system, but I'm not sure which information in the WKT-file is needed. Thanks!

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DanPatterson

open it up in a text editor and post what it says if you can't interpret it

Well-known text representation of coordinate reference systems - Wikipedia

FiveO

Thank you Dan! The link you shared was very helpful.

Based on that it seems the WKT-file includes conversion between two coordinate systems. Does this mean the Define Projection -tool should be used with the BASEGEOGCRS and then the Project Raster -tool with the information after CONVERSION?

The text file is attached here below.

Example_ESRI.txt

DanPatterson

You can right-click on the layer and select Properties and look at the extent values .... or

Open a new map, no basemap etc, just add the raster, set the map to display the coordinates of the raster. It will set the coordinate system for the map. scroll around, if the coordinates don't look like decimal degrees (eg small) then the raster was projected to... METHOD["Albers Equal Area",
ID["EPSG",9822]],

FiveO

The coordinates (and extent) are in meters so you're right, it was projected to EPSG 9822. I've attached an image showing the parameters I used for creating a new projected coordinate system based on the WKT. Does these look right? Thanks again!

NewPCS.png

DanPatterson

You don't need to create one if you know where it is for... pick one

FiveO

Thanks Dan! I know where the raster is/should be located (Alaska Albers) but the parameters of the projection in the ArcGIS selection do not match with the parameters in the WKT-file. However, I did try the Define Projection -tool and used Alaska Albers to see what happens, but the raster still opens at the origin of the projection grid (west of the island of Haida Gwaii, about 500 km out at the sea). Does this mean that the raster was created with wrong coordinate information?

DanPatterson

try creating it then... maybe it didn't use an Alaska albers (never know... Yukon is nearby 😉 )

FiveO

Neither Yukon or Alaska works, and even with the new one that I created based on the WKT the raster is still located in the middle of the sea. Is it safe to say now that something is wrong, or am I just not getting something?

DanPatterson

I suspect it is wrong then ... back to the source of the data to find out what is going on

FiveO

Thank you for your help Dan!

FiveO

An update to this question (after trying multiple ways of defining projection and projecting the raster):

It seems like the extent coordinates of the raster are wrong, which means it doesn't matter which coordinate system the files is set to as it will still use those wrong extent coordinates to locate the raster. How do I update the raster (not the map) extent coordinates? The extent should be around 125 W and 72 N (Amundsen Gulf). You see the original extent in the file attached. Also, the tfw-file of the rasters shows this:

0.6857400655 0.0000000000 0.0000000000 -0.6857400655 -10.2788462173 13.3755072589

Any ideas? Thank you!

UD_extent.png

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