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I have boundary data in WGS'84 lat/long and data in a custom generated CRS. The data in the generated CRS appears to be offset by a particular vector compared to WGS'84. I want to attempt to match the generated CRS projection boundary to the WGS'84 boundaries (seen overlayed on Landsat 7 imagery WGS'84 UTM zone 37N, 3 census datasets, yellow is WGS'84 and purple and red are both defined as the custom CRS on features)

3 census datasets, yellow is WGS'84 and purple and red are both defined as the custom CRS The custom CRS is listed here:

+proj=laea +lat_0=0 +lon_0=20 +x_0=0 +y_0=0 +a=6378249.145 +b=6356514.96582849       +towgs84=-160,-6,-302,0,0,0,0 +units=m +no_defs  

What datum is this?

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The transformation parameters you're using are for Kenya and Tanzania. If the data is only one of the countries, perhaps try another transformation? The parameters are:

Kenya: -157,-2,-299,0,0,0,0 Tanzania: -175,-23,-303,0,0,0,0

There's also one for Burundi: -153,-5,-292,0,0,0,0

Neither transformation has very good accuracy, but might give a better a fit. If that doesn't work, you could try this. Break down the offset vector into x and y components and add them to the +x_0 and +y_0 parameters. Unproject the data to lat/lon, WGS84. Now see how it overlays. You may need to do some tweaking to get this method to work properly.

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Thanks, that's right these are census sublocations for Kenya. Could you clarify "break down the offset vector into x and y components" ? –  XNSTT Mar 30 '13 at 19:52
    
Tried the suggested transformation for Kenya but it does not shift the sublocations boundaries visibly at 1:164178 scale –  XNSTT Mar 30 '13 at 20:06
    
even at 1:30000 scale no transformation visible –  XNSTT Mar 30 '13 at 20:30
    
@XNSTT, Let's say you measure the offset and it's 5 meters to the northeast. Figure out two offsets instead: east and north. In this example, it might 3 meters east, and 4 meters north. –  mkennedy Mar 30 '13 at 20:34
    
this works well for the sublocations near to the offset I measure but is less effective in all directions farther away. Would it be sensible to split up the sublocations? And if so by what magnitude in your opinion? –  XNSTT Mar 30 '13 at 21:22
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