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How to convert XY to Lat/Lon from unknown projection?

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#1
usego

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I have to export XY from legacy application to Lat/Lon. The problem is that this application renders map from it's own internal data files, which were populated from unknown shape files in uknown projection. XY are very low to be standart projection (1 <= XY <= 25000), may be those were scaled, but scale is unknown.

I've tried to convert XY using affine transformation by calculating affice coefficients by mapping source XY to "good" XY in known crossroads. But haven't get any good results.

Could you give any ideas please what else could I try?

#2
Esther Mandeno

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I have to export XY from legacy application to Lat/Lon. The problem is that this application renders map from it's own internal data files, which were populated from unknown shape files in uknown projection. XY are very low to be standart projection (1 <= XY <= 25000), may be those were scaled, but scale is unknown.

I've tried to convert XY using affine transformation by calculating affice coefficients by mapping source XY to "good" XY in known crossroads. But haven't get any good results.

Could you give any ideas please what else could I try?


If you are using ArcMap, one thought is to somehow convert the legacy line work to an AutoDesk drawing exchange file (DXF). Then add that as a layer into ArcMap. In ArcMap, geo-reference the DXF to some two known points using the transformation options (under the layers properties, one of the tabs available, can't remember which at the moment). Then export the DXF to a shapefile using the map coordinates. Whatever those coordinates happen to be, they would be known now and you can convert to lat/long or whatever. Hope that helps.
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Esther Mandeno
Life is like riding a bicycle. To keep your balance you must keep moving. - Albert Einstein




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