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Georeferencing a grid/raster

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#1
frax

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I just a had a case where a partner delivered an old ArcView 3 project, that included a raster which I needed for a map. I examined it, and I noticed that the raster was in Goode's Interrupted Homolosine, but it didn't have the proper coordinates. The raster covered a band of Africa, but without any features that would be useful for georeferencing (e.g. coastline).

I went through a convoluted procedure to get the coordinates and stuff right - not super-convoluted, but there was some trial-and-error involved.

* To get the correct target coords I converted coastlines into a grid using the exact same window and cell size, then I georeferenced this grid i ArcMap, and noted down the bbox coords.
* Then I exported my target grid to TIFF and manipulated the world file to match the bbox coords that I had just retrieved.
* Converted back the TIFF to grid and fixed some minor stuff along the way (e.g. 16-bit unsigned conversion)

I did some of this work in ArcInfo workstation - since i know this better than ArcMap/Toolbox...
Hugo Ahlenius
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#2
mdsumner

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What format was the raster in? Are you sure there was no georeferencing in any auxiliary files?

#3
frax

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The raster was in ArcInfo grid format, and it was georeferenced, but without any projection information and with the coordinates off.
Hugo Ahlenius
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#4
mdsumner

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ASCII or ADF, or something else?

#5
frax

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arcinfo grid format, see previous post
Hugo Ahlenius
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#6
mdsumner

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arcinfo grid format, see previous post


Sorry if I'm not being clear. Is the file format the ASCII or binary version of "arcinfo grid format"? One is simple text, with georeferencing at the start of the file, with projection support via .prj file. The other is binary, called "ADF" composed of a number of binary files.

#7
frax

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mdsumner - I am referring to the binary format, that is what I know as arcinfo grid format, in an arcinfo workspace.
Hugo Ahlenius
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