A map projection is any method of representing the surface of a sphere or other three-dimensional body on a plane
4
votes
2answers
217 views
Why isn't valid geometry not valid in NetTopologySuite when close to poles?
I have a Polygon which crosses the south pole:
Polygon in WKT:
POLYGON((5.86826073458095 75.6638564054071,-16.5436836399021 63.2220742891438,-19.3664667294083 59.846221066959,-21.7009816876343 ...
4
votes
1answer
439 views
How to use DotSpatial to project/reproject shapefiles on the fly
I would like to use DotSpatial to reproject shapefiles on the fly before loading them to GeoServer. I've been looking for tutorials on how to get started with this in vain. Any pointers on where I can ...
4
votes
1answer
761 views
Distances in {Plate Carrée projection - EPSG:4326 - WGS84}
So,
"4326 is just the EPSG identifier of WGS84" [3], indeed http://spatialreference.org/ref/epsg/4326/html/ says it is a GEOGraphic Coordinate System:
GEOGCS["WGS 84",
DATUM["WGS_1984",
...
4
votes
1answer
235 views
Projecting gps data to get length of resulting line shape in ArcMap 10.0
I have gps data in WGS84 geographic coordinates. I will use the gps data to build a line shape in ArcMap 10.0. The data falls in UTM 15N.
To get most accurate length of line, should I project the ...
4
votes
0answers
186 views
How can I improve my Georeferencing results?
Background This is my second question related to georeferencing naked raster maps in order to re-visualize them on different coordinate systems and in conjunction with other data layers. The previous ...
3
votes
1answer
495 views
Is there a simple way to compute the UTM Zone from a lat/long point?
I am trying to convert a latlong point to UTM. To define UTM projection, I need to calculate zone for the point. I am trying to figure out the best way to do this. One way to do this would be use ...
3
votes
2answers
198 views
What projection is this in GDAL classification
I need to re-project a PNG from a given projection to the Google maps projection.
I have a grid of the source projection, looks like a Mercator projection.
What is the exact name of this projection in ...
3
votes
3answers
149 views
How to reproject to other projections than WGS84 or Webmercator?
I have an OpenLayers map with a vector layer to add points on. I'm using Google Maps as the base layer. After the point is added, I need to store the data in my database as lat/long and x/y. Can I ...
3
votes
2answers
505 views
How do I get the distance meter value between two geometries in PostGIS?
I have a simple question about calculating distances in PostGIS.
I would like to get the distance between two geometries. I am using this sid : 4269 in meters
what i am doing now is this : ...
3
votes
1answer
169 views
How would I go about re-projecting the Blue Marble raster maps into a robinson projection using free tools?
I would like to convert the NASA Blue Marble maps into a robinson projection.
3
votes
1answer
721 views
Matching ArcGIS and QGIS coordinate systems
I have the following info for a feature class in ArcGIS that is supposed to be in WGS 1984/UTM 16N projected coordinate system:
Projection: Transverse_Mercator
False_Easting: 500000.000000
...
3
votes
1answer
1k views
OpenLayers doesn't show an overlay with a different SRS than the base layer
I need to add an overlay layer that uses EPSG:4326 to a map with a base layer that uses EPSG:32628.
Every time I add the overlay OpenLayers automatically switches the SRS param of the overlay to ...
3
votes
3answers
257 views
Is there a projection issue with the NRC Canada Atlas hydrology data?
I have been using the Natural Resources Canada (NRC) data for various generalized maps but it is not until now when i overlaid higher resolution features obtained from the provincial government ...
3
votes
1answer
57 views
What is displayed when I am using a geographic CRS for my project
I understand that each geographical dataset has a CRS, and that in order to overlay them, you need to either make sure that all datasets use the same CRS, or re-project some of them (or use on-the-fly ...
3
votes
2answers
343 views
German coordinate system from Lat/Long
I have WGS latitude and longitude for data points near Munich and I'd like to use a grid-type coordinate system, like the Ordnance Survey grids in Ireland or the UK. What coordinate system do you ...
3
votes
2answers
140 views
Can you search WMS services for a particular projection?
Is there an interface or website to search public WMS services for location/projection?
3
votes
4answers
332 views
Determine Projection
I was given a shapefile at work with the information that it is in Lambert Azimuth Equal Area (LAEA) projection (EPSG 9820). After some research on the web, I found out that EPSG 9820 is a generic ...
3
votes
2answers
2k views
How to read projection information from .dwg file
I have got an Audocad .dwg file which is based on some location of sweden. But i dont know what is the internal projection of this file? how i get projection information from this .dwg file.
Actually ...
3
votes
3answers
8k views
Calculate projected area of polygons with field calculator in ArcMap 10
I've got a polygon featurelayer in arcmap.
The coordinate system of the featurelayer's featureclass is web mercator.
The dataframe of the map uses an equal-area projected coordinate system.
I've ...
3
votes
2answers
644 views
Which ESRI defined geographic transformation do I need to use to convert my “ NAD83 Northern Virginia” data into WGS 1984 Web Mercator?
My title pretty much tells it all..
I have a number of datasets in which I want to batch project from NAD83 Northern Virginia Datum into the correct Web Mercator projection..
When I do a straight ...
3
votes
1answer
264 views
How to re-project ease( Equal Area Scalable Earth) grid with a ~25 km cylindrical projection to WGS84 0.25 degree?
I have nc (NetCDF) files for global soil moisture.
From the metadata, the projection is cylindrical and the resolution is 25 km (it is based on authalic sphere based on International 1924 ...
3
votes
1answer
147 views
Why are two incompatible projections used together in OpenLayers? [duplicate]
While going through the examples in OpenLayers, I notice several examples with the following code:
map = new OpenLayers.Map('map_element',{
...
units: 'm',
projection: new ...
3
votes
3answers
488 views
Convert an arbitrary meta-data-free map image into QGIS project
My background: experienced programmer, amateur historian, complete beginner to GIS (so I'm using QGIS). I did learn to use the QGIS georeferencer tool though.
The input: suppose I have an image like ...
3
votes
1answer
282 views
Is a WMS map always a constant scale?
If I get a map back from a WMS server is the scale always constant over them map regardless of the reference system?
So if I have a map which is 100 pixels wide, will the point at 50 pixels always ...
3
votes
1answer
94 views
how can I know which projection has this data?
I have data in an unknown projection to me.
I open it in QGIS and I see that the shapes are ok, but I need to identify the projection in order to merge this data with other stuff.
The points look ...
3
votes
1answer
157 views
getting the specified geographic transformation, or at least the GCS, of a data frame
First, the TLDR digest:
I'm getting a bogus value from dataFrame.geographicTransformations on some machines; how do I get the correct value as shown in the properties dialog? and/or
Given a spatial ...
3
votes
1answer
147 views
2 Shapefile vectors will not plot properly in same space
There are slight differences in 2 shapefiles projection information. I have activated on-the-fly, but they do not plot in the same space. I tried to save as new shapefiles with the same CRS, but ...
3
votes
2answers
484 views
Display two layers with OpenLayers at once
How can i display two layers with diferent projections at once? For example i have layer with EPSG:70076 and OSM layer.
3
votes
2answers
155 views
How do you change the prime meridian of a map?
I am working with the Natural Earth world map as a SHP file, but when I try to change the prime meridian (PRIMEM) of the coordinate system
...
3
votes
1answer
230 views
Ogr2ogr projection problem- features are shifted 12 miles to the north?
I have discovered a problem related to the output of an ogr2ogr command line call. My resulting polygon features are 12 miles (.18 degrees) due north of where they should be, but the longitude is ...
3
votes
1answer
327 views
How to solve Projection Problem at client side
I want to discuss a scenario here to all.
I have developed a Web mapping application in OpenLayers and GeoServer. The customer give us shapefiles with native projection SWREFF99_1330 (EPSG:3008). ...
3
votes
1answer
204 views
ArcGIS 10.0/10.1 - arcpy - automate projection tool with different datum or projection
I am getting stuck with a task that is slightly different from the posts I found so far on this same website.
Assumption: all layers have a defined coordinate system
Problem: I would like to ...
3
votes
1answer
79 views
Projectionless shapefile with unknown source
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 ...
3
votes
1answer
149 views
How to reproject a raster to Winkel Tripel projection?
I'm trying to project a raster map (in ASCII grid format) from longlat to the Winkel Tripel projection. But I'm running into errors, for instance gdalwarp won't accept the proj-string.
$ gdalwarp ...
3
votes
1answer
145 views
Is there no EPSG code to use for Behrmann equal-area projection in ogr2ogr?
I'm trying to use ogr2ogr to reproject some shapefiles. The projection I wish to use is Behrmann equal-area. I cannot find an EPSG code to use for the '-t_srs' part of the syntax. Is there any way ...
3
votes
2answers
189 views
Is NAD 83 the same as EPSG:4326?
I'm getting mixed messages about these projections.
For example -Is this projection below, NAD 83, 4326?
GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",
...
3
votes
2answers
510 views
How to calculate how long an arc second is for a given long/lat?
The title says it all, really. I am wondering what area is covered by a dataset which is one arc second wide.
Thanks,
Rob
3
votes
3answers
345 views
Convert Nasa's Blue Marble into a cubic projection
I'm looking for a free tool to convert the cylindrical projection map of the Earth's surface that you can get from Nasa (under the Blue Marble project):
...
3
votes
1answer
554 views
How to perform datum transformation in ArcGIS server REST API exportmap
I have a ArcGIS server 10.0 mapcontext in one projection (swedish grid sweref99 TM) which uses its own datum, also named Sweref99 . When I use the REST API's map service export function I want to ...
3
votes
1answer
388 views
How can I specify a PROJ.4 projection with the north pointing *down*?
I would like to create a world map "upside down", with the south on top (in Mapnik).
Can I take an existing projection string, e.g. Robinson projection
+proj=robin +lon_0=0 +x_0=0 +y_0=0 ...
3
votes
1answer
276 views
Equal Area SRID for Australia
This has been bothering me for some time so I figured I would put it out there.
Does anyone know the SRID for an equal area projection that is suitable for the whole of Australia?
I realize that I ...
3
votes
2answers
274 views
How does ESRI, and how should anyone, transform a coordinate that lies outside a grid transform (e.g. NADCON)?
As I understand it, a datum transform (e.g. urn:ogc:def:coordinateOperation:EPSG::1241) based on a grid interpolation method, e.g. NADCON, is undefined outside of the grid of points. Therefore the ...
3
votes
1answer
71 views
What's the difference between Geographic coordinate system 4019 and 4121?
I have a DEM with cell size 100,100 with geographic coordinate system GRS_1980_Transverse_Mercator, Datum: D_GRS_1980. I created some extra shapefiles with projected coordinate system: Greek_grid, ...
3
votes
1answer
56 views
Which Geographic Transformation to use for WGS_84 to D_Sphere?
I have a shapefile for world countries and I want to reproject it from GCS_WGS_1984 to Sphere_Eckert IV. However, it asks for Geographic Transformation; it says this is optional but it is required in ...
3
votes
1answer
136 views
High Resolution Sinusoidal Interrupted Projection of the Earth
My grandfather built a rather large globe 10 years ago and never got to complete it (he started drawing about a fifth of it by hand and just gave up after that).
I have been looking for a sinusoidal ...
3
votes
1answer
424 views
Openlayers and Geoserver fail to reproject while editing Vector with WFS-T
I can't get the Openlayers and Geoserver work with WFS-T editing a vector layer.
I have a layer of points where the Native SRS is EPSG:32639.
After trying a lot of combinations, I ended up with two ...
3
votes
2answers
732 views
Setting the map projection in the flex API to an overlay layer
I'd like to use a basemap containing world map data as a backdrop to some point and outline data that I'm hosting in ArcGIS server in the ESRI Flex API, but I would like the map control to share a ...
3
votes
1answer
25 views
Does IDistanceOP.EucDistanceFull require a projected coordinate system?
I have designed an implementation of ArcObjects' IDistanceOP.EucDistanceFull. It takes its input as a feature class and converts it to a GeoDataset with which EucDistanceFull can work with. It works ...
3
votes
1answer
69 views
Compute global DEM topographic indices and compromise projections
I would like to compute global topographic indices based on SRTM elevation data. These indices are computed along river/channel networks extracted from a DEM and are a functions of both local slope ...
3
votes
1answer
273 views
Leaflet and EPSG 4326 Projections
Leaflet says it supports EPSG 4326 (Plate Carree, aka ll84) projections. I think it does, but take a look at these two jsfiddles:
http://jsfiddle.net/drysg/cBzVc/ - This is the original 3857 web ...
