I am having projection issues with OpenLayers version 2.13 with MapServer and the Proj4 library. Pulling layers in NAD83 State Plane Feet projections on top of an OSM or MapQuest Base Map in Google EPSG:900913 / EPSG:3857 is working perfectly in most locations. However there are some states where an identical setup does not work, specifically Alaska and Vermont.

Alaska and Vermont are two cases where there is not an EPSG code for NAD83 State Plane Feet (only meters), but there are Esri codes in Feet. In Alaska I have tried ESRI:102631 (NAD 1983 StatePlane Alaska 1 FIPS 5001 Feet) and this works well in MapServer alone but the layers do not show in OpenLayers.

We have not upgraded the MapServer installation and Proj4 in a couple of years, so maybe a new version will help, but since things are working well in MapServer I think the issue is in OpenLayers. I have also tried creating a custom EPSG definition with no luck.

I am not sure what to try next for troubleshooting. Are there any issues in OpenLayers when using Esri codes? Should we be using NAD27 in these states? That would be OK except that we have a lot of imagery in NAD83 Feet that should probably not be converted to different a projection.

Here is the definition we are using in OpenLayers (NAD 1983 StatePlane Alaska 1 FIPS 5001 Feet):

Proj4js.defs["ESRI:102631"] = "+proj=omerc +lat_0=57 +lonc=-133.6666666666667 +alpha=-36.86989764583333 +k=0.9999 +x_0=4999999.999999999 +y_0=-4999999.999999999 +ellps=GRS80 +datum=NAD83 +to_meter=0.3048006096012192 +no_defs";
  • Followup: I see in the Proj4js documentation that Oblique Mercator (omerc) may not be supported. Could this be the issue? It states: "The following projection classes have the forward and inverse transformation code available for them but have not been validated against any test points yet:" Is there a workaround? – maptheworld Dec 28 '15 at 4:25

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