I have a bunch of maps that are output from a land use model in .asc format, but none have a projection file associated. The person who originally ran the LU model is long gone, so I don't have access to the files that were the original input to the model. I've gone through http://spatialreference.org and ad-hoc tried to fit my data to all the projections that looked remotely worth trying, as suggested here and in links within.

Details: Using ArcInfo 10.0. Data is for China. Gauss-Kruger projections came close to looking correct (after on-the-fly projecting on top of my known reference data), but were still several hundred km off in places and somewhat distorted. I think my only recourse is to manually project these projectionless shapefiles - which really sounds like a non-solution to me. Anyone have thoughts on a better fix?

Here's the extent info Top: 5924000 Left: -2638000 Right: 2210000 Bottom: 1870000


  • I'd try the most common ones: - WGS84 - EPSG4326 - Google Mercator - EPSG900913, EPSG3857 And I assume it's the 2. one. ;)
    – Styp
    Commented Nov 10, 2012 at 11:05
  • The data sounds fairly old, considering the history and ASC format. I would not assume the projection is Google/Web Mercator, or any related reference such as EPSG:4326.
    – user3461
    Commented Nov 10, 2012 at 11:21
  • 1
    If you don't get an answer here, you may want to ask at lists.maptools.org/mailman/listinfo/proj - a lot of experts are subscribed. I had good success in the past there guessing e.g. WWII coordinate systems.
    – markusN
    Commented Dec 1, 2012 at 11:33
  • Can you check the geometry and at least see if it is likely projected(meters or something) or geographic(degrees)?
    – user10353
    Commented Dec 31, 2012 at 15:46

1 Answer 1


I agree with @Kevin, I don't think it would be projected in Google Mercator, as it sounds too old-school, and that's never been considered a serious projection by the science community.

If you know approximately where the data should be in China, I would recommend trying the most-appropriate UTM projection for the given area. If the data straddles a zone boundary, start with the zone that it spills into the most.

This map of UTM zones might be helpful: http://www.dmap.co.uk/utmworld.htm

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