topic Re: ArcGIS - WGS 84 Transformation conflicts with other platforms in Data Management Questions

ArcGIS - WGS 84 Transformation conflicts with other platforms

SatishKumar3 — Thu, 08 May 2014 09:33:06 GMT

I have rasters, need to be geo-referenced in WGS 84 datum with Lat/Log (degree). I have geo-referenced using Global Mapper, which we usually used to use, because of its user friendly. Got a vector data of the same raster through other sources, which also used GCS_WGS 84 (Could have been geo-referenced using ArcGIS with GCS_WGS84). When I overlap both the data, found off-set about 300 meters. Checked all data origins and geo-referencing, everything correct, still off-set unavoidable.

To check further, I have geo-referenced same raster with GCS_WGS84 in Global Mapper and ArcGIS seperately. I found the same off-set of 300m.

Is that really different transformation applied in difference platforms, or any other parameters related to this??

Re: ArcGIS - WGS 84 Transformation conflicts with other platforms

MelitaKennedy — Thu, 08 May 2014 13:58:42 GMT

Also asked on gis.stackexchange.com.

ArcGIS for Desktop with geographic/datum transformations is a late-binding system. We do not link a default transformation to a particular geographic coordinate system. When data needs to be transformed, then you set the transformation that you want used.

It's possible that Global Mapper is an early-binding system that sets a default transformation per geographic coordinate system.

Because of the size of the offset, I think no transformation occurred in ArcGIS.

Melita

Re: ArcGIS - WGS 84 Transformation conflicts with other platforms

GlennBrooks — Fri, 06 Jun 2014 20:14:40 GMT

I have a similar problem.

Using Global Mapper, I created a simple shapefile having 9 adjacent shapes laid out in a rectangle. I used this layer to clip aerial imagery to the boundaries of each feature in the shapefile using Global mapper. the clipped shapes are exactly coincident with the polygon edges.

When I import both the shapefile and cllipped images into ArcMap V10.2, the shapes and imagery become offset approximately 1.5 meters. Also, The latlong of a known point in the polygon/imagery overlap in ArcMap is hundreds of meters offset from the lat/long of the same point in Global mapper.

Also when I load the data in QGIS the layers are all conincident, only when I load into Arc10 are they not coincident.

In global Mapper the projections are:

shapefile: WGS84 - lambert Conformal -Washington State Plane South -feet (US Survey)
Imagery: WGS84 - Geographic ( lat/long) - Arc Degrees EPSG Code 4326 (obviously not Wash State Plane-South)

Problem 1: How do I correct this overlap to achieve coincident data in ArcMap?

Problem 2: In Arcmap I went into Catalog image file/properties and changed the image projection to State Plane South - the image file then disappeared from the screen and would not display. reset the original projection and it re appeared.

Thanks
Glenn