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location Redlands, CA
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visits member for 3 years, 9 months
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I've been working with map projections and datum transformations for years, including in ArcView GIS, ArcInfo 7 and up, MapObjects, and ArcGIS.


1d
comment Projecting INEGI shapefiles from Mexico
Apply by redefining or reprojecting? Use the project tool, not Define Project tool or the data's property page.
1d
reviewed Approve suggested edit on Having trouble with clipping tool giving incorrect shape
1d
answered Projecting INEGI shapefiles from Mexico
Jul
14
comment Wherer is wrong with transforming a WGS84 [lon,lat] point onto google maps
You have to either use a = b = 6378137.0 m with a standard ellipsoid-supporting Mercator implementation OR use a Mercator implementation that supports spheres only. The error is when you converted to XYZ using WGS84, then back to lat/lon using the sphere. That changed the latitude values which is not needed to match Google's data.
Jul
14
answered What is the Login to the ESRI FTP site for Arc Hydro Tools?
Jul
11
comment Why can't I reproject from HARN State Plane Ft Intl to State Plane Ft?
I created a map projections 'group' - but just tag any content with "map projections" or "projections" and I'll see it. Check presentations from early Dev Summits. I think the UC ones aren't available, but you can try those too.
Jul
11
comment Why can't I reproject from HARN State Plane Ft Intl to State Plane Ft?
Checking tfm results means comparing against some other corresponding known to be in the output coordinate system or by knows what the offsets/target values should be. Check the geographic_transformations.pdf file in ArcGIS home, Documentation folder and go by area of use and accuracy.
Jul
11
comment Why can't I reproject from HARN State Plane Ft Intl to State Plane Ft?
If you're comparing the original and reprojected datasets in ArcMap, did you set the transformation there too? Use the same transformation that you used in the tool. If you're comparing the reprojected data against other/reference data, check the original against it. Maybe the reference data is already using "HARN" and its metadata is incorrect.
Jul
11
reviewed Approve suggested edit on How to determine in which grid cell where each coordinate of an x,y series is located?
Jul
10
revised Why do converting GPS points to polygon using ArcObjects differ from manual converting?
mostly corrected spelling, fixed code formatting
Jul
10
reviewed Close How to cancel tool execution in python
Jul
10
reviewed Approve suggested edit on How do I make a picture marker symbol at a given latitude and longitude in ArcGIS for Javascript?
Jul
10
comment Raster projection fails without error
Did you set a transformation? Although the tfm is a 'null' one (no changes), so you could just use Define Projection to change the metadata.
Jul
9
comment Raster and vector layer in the same CRS don't match
The raster layers are UTM zone 32N. The GeoCRS (datum) could be ED50 or ETRS89 or Roma 1940 / Monte Mario. That's if the sample point is in Bologna.
Jul
9
comment Can't find correct coordinate system: UTM83 Zone 15 forcing input in meters; need it to be read in feet
OP needs nad83, not nad27, so EPSG:32165.
Jul
9
comment Can't find correct coordinate system: UTM83 Zone 15 forcing input in meters; need it to be read in feet
Look for BLM zone 15N, which is the same as UTM 15N, but using US survey feet for the unit.
Jul
9
reviewed Approve suggested edit on Creating a 10-mile radius buffer zone that averages a variable in my shapefile?
Jul
9
comment QGIS to solve projection mystery in Postgresql
I agree with @ChrisW that you transposed 3857 as 3587 because you've circled Texas and the Gulf of Mexico, NOT Michigan. Please double-check with the data provider what the CRS is.
Jul
9
comment Postgis: Traslate geometry from EPSG:23030 to EPSG:21818, then to lat long
I'm just commenting because @paul-ramsey should update his answer as he has the PostGIS info. The data is using EPSG:21897 Bogota 1975 / Colombia Bogota Zone. If you need to convert to WGS84, the tfm is "coordinate frame" dx=221.899 dy=274.136 dz=-397.554 rx=2.808446 ry=-0.448509 rz=-2.810172 s=-2.199943. In ArcGIS the tfm is "Bogota_To_WGS_1984_Region_8_CF". Also, always say where the data is (the city), luckily you'd included the screenshots and I could find out that it was Paipa.
Jul
8
comment Postgis: Traslate geometry from EPSG:23030 to EPSG:21818, then to lat long
Can you include in your question a sample coordinate pair from your "EPSG:23030" data? If they're showing up in Nigeria, then the metadata information is incorrect. Could they instead be in whatever UTM zone is appropriate for that area of Colombia?