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comment Approximating GPS coordinates for a point from n expected locations
+1 Nice solution!
22h
revised Why I see a gap between ESRI Robinson WGS84 (EPSG 54030) VS QGIS Robinson WGS84 (EPSG 54030)?
added note re: sphere
23h
comment Why I see a gap between ESRI Robinson WGS84 (EPSG 54030) VS QGIS Robinson WGS84 (EPSG 54030)?
I'm getting much closer answers if I specify a sphere in PROJ.4. I've been trying various values but none are exactly matching the same sphere in ArcGIS.
23h
answered Why I see a gap between ESRI Robinson WGS84 (EPSG 54030) VS QGIS Robinson WGS84 (EPSG 54030)?
1d
comment Why I see a gap between ESRI Robinson WGS84 (EPSG 54030) VS QGIS Robinson WGS84 (EPSG 54030)?
@AndreJ It's true. We thought of that, but afaik, PROJ.4 requires +R*=value, so that shouldn't be a problem. Jerome - the prj/qpj files didn't include the PROJ.4 string. What is it in QGIS?
1d
comment What coordinate NOTATION would this be?
Do you have any idea what location the data represents? That is, city, lake, intersection...Using that, someone can try out different coordinate systems used in the area to see if there's a match.
1d
reviewed Leave Open Auto refresh of mapservice
1d
comment Why I see a gap between ESRI Robinson WGS84 (EPSG 54030) VS QGIS Robinson WGS84 (EPSG 54030)?
Dev thinks the different interpolation grids could be the culprit. I don't have PROJ.4 (or any SW that uses it) running. Do you have any test points at even 10 degree intervals? Those should give the same answers.
1d
comment Why I see a gap between ESRI Robinson WGS84 (EPSG 54030) VS QGIS Robinson WGS84 (EPSG 54030)?
@AndreJ but I don't have an answer yet, just speculation!
2d
comment Why I see a gap between ESRI Robinson WGS84 (EPSG 54030) VS QGIS Robinson WGS84 (EPSG 54030)?
The projections are set up differently--PROJ.4 has pre-calculated values every 5 degrees before it interpolates. Esri uses the table from the original paper, which isn't as dense. I'll have to see what a developer thinks. Esri also has a Robinson (ARC/INFO) version. That gives different answers. It was implemented by a contractor probably 25-30 years ago (before me) and we're still not sure why it's different.
2d
comment Why I see a gap between ESRI Robinson WGS84 (EPSG 54030) VS QGIS Robinson WGS84 (EPSG 54030)?
The difference in deg-rad conversion isn't enough for mm differences let alone km differences. Let me think about it (I'm the Esri projection specialist).
Sep
1
comment Georeferencing CAD drawing with 1 control point
@wittich In ArcMap, CAD data has a special georeferencing option. It uses two points only (for 2D Helmert/similarity/conformal transformation) or you can use scale/rotate/translation values if you have them.
Sep
1
comment How to recognise building type from polygons?
Perhaps try to find some zoning/planning information? That won't help 100% though.
Sep
1
comment QGIS to Leaflet Projection Weirdness
If you built the hexagons in lat/lon, I would expect north-south stretching if reprojected to Mercator (any Mercator, not just EPSG:3857).
Aug
31
comment ArcGIS: Goode Homolosine Projection and Inconsistent Extents
You could trim the raster to remove the offending row/column. But if you're checking values within a polygon, then the existence of an extra row or column at the edge of the raster shouldn't matter.
Aug
31
comment What's the formula for converting SWEREF99 to WGS84
Yes, robust means good where good means 'supports an adequate range of longitudes at mid- to -high latitudes. Some transverse Mercator algorithms use series expansions in the calculations. if the series doesn't have enough terms, longitude calcs on inverse (from xy) start to not work at 8-9 degrees--less at higher latitudes.
Aug
31
reviewed No Action Needed How to get images displayed on ArcGIS Online Popups
Aug
31
reviewed Approve change SRID of shapefile and QGIS
Aug
31
comment Reading NOAA CPC REF VER 2 data for Precipitation
Did you ungzip it? gz extension = gzip. What format is it after you ungzip it?
Aug
31
comment About defining coordinate reference system
I'm not sure why this was closed. Both questions are answerable. For Q1, you know the answer already--the "unknown" data was already in the map/data frame's coordinate system. When data has no coordinate system, the software can only display it. For Q2, the software has no way of knowing that the data is lining up or not. Well, it could check the extents, but wouldn't be able to know for sure.