A map projection is any method of representing the surface of a sphere or other three-dimensional body on a plane
1
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1answer
377 views
When I import polygon kml layer, how do I change projection and offset to correct for GMT wrap?
I created a polygon in Google Earth and saved to kml. After importing as a vector layer, where the polygon crosses the prime meridian, the polygon wraps around the world.
So far, I have figured out ...
0
votes
2answers
2k views
How to create custom coordinate system in ArcGIS?
I have a series of control points with xy coordinates in both NAD83 UTM and in a local grid.
How can I go about creating a new projection file in ArcGIS 10 for the local grid?
Thanks
3
votes
0answers
254 views
How to define Winkel Tripel in proj 4.8.0?
I have QGIS with proj 4.8.0 installed. I'd like to add Winkel Tripel projection which seems to be defined as
+proj=wintri
But that definition string does not work. Is this a bug in my proj version, ...
17
votes
7answers
538 views
Spatial reference for dummies?
Can anyone recommend a good reference or tutorial that explains the principles of spatial references, projections, and coordinate systems? We are a small team of programmers working with GIS ...
1
vote
0answers
113 views
How to show an array of 2d points/polygons in Polymaps (Cartesian coordinate system)
I need to display these 2d points/polygons (Cartesian coordinate system) on Polymaps with GeoJson layer.
I do not use the other layers.
Do I need to convert xy coordinates to the lat lon? If so, how?
...
2
votes
1answer
1k views
How to convert decimal degrees units to km in R?
I am trying to figure out how I can transform my unit of length from decimal degree to km when I import the following simple ArcGIS polygon shape. Ultimately, I would like to have this information ...
3
votes
1answer
582 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 ...
2
votes
1answer
242 views
Is it possible to automatically set CRS of Rasters from PRJ file?
I am trying to learn my colleagues to display measured data (ASCII) in maps relatively easily. I can prepare project, color and symbology style for the point layer and background map.
I also found ...
1
vote
1answer
285 views
Looking for help identifying projections and reprojecting
Hi there at the new forum,
I'm still struggling with projections in qgis. The "Vogelschutzgebiete" reprojection worked. But these ones seem to be tougher:
...
0
votes
0answers
49 views
What projection is this [duplicate]
Possible Duplicate:
QGIS - Hell of time with CRS and vector intersect
The tax assessor parcels layer I referred to in my first post gives this as its projection:
+proj=lcc ...
10
votes
2answers
183 views
How do I determine the projection of a paper map?
If I'm reading a paper map how do I determine what projection was used to draw the map if such information is not explicitly labelled on the document?
Online it is easy to find resources (for ...
2
votes
2answers
692 views
Image tiling math
I've been looking at MapTiler for the logic on how to render an image
as tiles on a (google) map. Instead of storing the single tiles
locally in a folder structure I want to use Djatoka. I'm able to
...
1
vote
0answers
249 views
Geoserver tiles mismatch
I tried to get WMS tiles from geoserver like
/geoserver/gwc/service/tms/1.0.0/layername@EPSG%3A4326@png/15/19142/9530.png
or with another projection
...
3
votes
1answer
174 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.
2
votes
3answers
1k views
Rendering a shapefile with a custom projection in GeoTools
I have an image, a shapefile, and a method which can translate an x/y pixel location from the image into a latitude/longitude point or vice versa. I'm trying to use Geotools to render the shapefile on ...
2
votes
0answers
82 views
raster data expressed as percent
I downloaded NDVI greeness data from the USGS Integrated Vegetation Mapping Viewer. In the metadata it says that visual greenness values range from 0 to 100. My data is from the period ending 3/5/12 ...
1
vote
2answers
259 views
Geowebcache re-projection
I have one layer (raster geotiff image) published in geoserver with EPSG: 3011 projection. But I want this layer in EPSG 4326 projection for use it in google API web application. I have searched on ...
0
votes
2answers
66 views
Need Image with Sweref99_1800 projection/coordinate system
I need third party image tiles (probably world imagery) under sweref99_1800 projection and coordinate system (EPSG 3008). I found this link ...
2
votes
3answers
733 views
Why are the tile coordinates different in Google maps and Google earth?
I have a .NET application that typically uses the standard Google Maps JavaScript API V2. Within this application I am using a GTileLayerOverlay to add my own custom dynamic tile layer.
function ...
5
votes
2answers
1k views
How is EPSG:4326 data 'projected' in a 2D map?
I like to think I'm relatively well-versed in datums, projections, and coordinate reference systems, so if this is a stupid question I will suffer eternal shame.
OpenStreetMap data is stored in WGS84 ...
0
votes
0answers
65 views
Changing projection of base layer
normally we change projection of vector data for displaying it over google base map. Similarly is it possible to change the projection of base image tiles map? if yes, how we can do that, any ...
14
votes
2answers
548 views
Which world map projection allows comparing countries by shape and size?
The Mercator projection increases scale along with the latitude. Greenland seems larger than Australia, when in fact it is much smaller. The equal-area projections however stretch shapes away from the ...
5
votes
1answer
926 views
Mercator projection: problem with latitude formula
I'm trying to get the position of a coordinate on this map (source Wikipedia):
If I'm correct than the formula for the position of the latitude would be:
R * ln(tan(pi/4 + latitude / 2))
But ...
12
votes
3answers
5k views
Layers having the same coordinate system should overlap, but they don't. What's wrong?
I put 4 different layers into my ArcMap document, but only one of them will show up on the map! I should be seeing the other 3 layers as well. When I do a Zoom to layer, I can see one layer, but I ...
13
votes
1answer
2k views
How to define new custom projections in QGIS?
I'm trying to define a projection in QGIS. I want to add North America Albers Equal Area Conic. From the spatialreference site I copied the proj4 line:
+proj=aea +lat_1=20 +lat_2=60 +lat_0=40 ...
2
votes
1answer
601 views
How can I transform GCS_WGS_1984 to GCS_North_American_1983?
I need to convert a GCS_WGS_1984 data set to NAD_1983_UTM_Zone_14N. What transformation should I use?
2
votes
4answers
2k views
OpenLayers transform EPSG 27700 coordinate to Google 900913
Community,
I'm currelty capturing my mouse click event and trying to transform the coordinates into Long Lat. I need to get at the Long Lat as strings so I can build a url and throw it at Google ...
1
vote
0answers
127 views
I am getting a blank layer preview from geoserver after Quick Exporting my shapefile to postgis and then getting postgis to point to geoserver
What could be the potential problems? Looking at the layer's data fields/form the one thing that isn't filled is the Native SRS and its source, but I have already passed in the projection info as it ...
6
votes
1answer
154 views
What's a robust strategy for displaying 3D map data for navigation?
3D map data, specifically the kind you see on GPS units, or more recently on smart phones, almost always features a 'HUD' like view, which I'm trying to implement in an application of mine. I have ...
1
vote
1answer
333 views
Converting distance between nautical miles and degrees
This is such a basic question that I'm kinda of embarassed. Here is the situation:
We have a certain funcionality developed that:
Will check for a tolerance value (this input is given by the user ...
9
votes
2answers
1k views
API documentation for Gdal/Ogr with C#
I want to assign projection to shapefile in my web C# application, for this i am using Gdal/OGR/OSR C# bindings and add osr_csharp.dll and ogr_csharp.dll references. But i am facing some difficulty ...
2
votes
1answer
218 views
Possible to use Google Earth to generate “skyline” planes?
I was really interested to notice that my city appears to have gotten the 3D Buildings treatment on Google Earth. I am trying to figure out how I might these 3D buildings to generate 'skylines' for a ...
1
vote
1answer
175 views
Defining multiple projections inside a file gdb [error 000289 failed to alter spatial reference]
I am importing multiple shapefiles into a filegdb in ArcGIS 10, and using the following code to define the projection of the feature once imported, to the .prj of the original .shp file.
Here is my ...
4
votes
5answers
972 views
How to add a projection to a Shapefile using open-source tools?
I have been given some shapefiles WITHOUT a projection. So I need to add the projection in order to display it on google map. I found the projection information I need at ...
1
vote
1answer
220 views
Best practices to minimize error when buffering unprojected data
If I buffer hundreds of unprojected WGS84 points across the US by say, 3 miles, will I get accurate areas returned (3 x pi x r) for each of the circles created? I suspect not. If not, what would be ...
9
votes
1answer
367 views
How to create an Azimuthal Equidistant map for long-distance radio?
I'm trying to produce world or continent scale maps that use the Azimuthal Equidistant projection. I'm a radio amateur, and to an antenna, the whole world looks like spread out on a flat plane, with ...
11
votes
3answers
1k views
Do ArcGIS SpatialReference object factory codes correspond with EPSG numbers?
I've got a project where I'm reading in geometry objects from text files to put them in ArcSDE. These geometry objects have an associated EPSG code, and I'm looking for a way to ensure they're in the ...
4
votes
1answer
241 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 ...
9
votes
2answers
668 views
How can I make a polyline wrap around the world?
I am using leaflet maps to create a representation of a round-the-world challenge. I would like to add a polyline which heads east from tokyo and then appears west of south america on the map - but ...
2
votes
1answer
872 views
Quantum GIS Reproject a projected coordinate system with rotation
I have two shapefiles:- one in WGS84 Z30S and one in a custom, system based, projection. I need to convert the custom projection into WGS84 Z30S.
I have a set of parameters including a shift in X and ...
2
votes
1answer
471 views
What is wrong with this Proj4 transformation?
I'm implementing support for WMS maps in my company's software. Servers return a list of projections their maps are available in, but our software only displays data in WGS84 (lat/lon or UTM), and ...
1
vote
1answer
456 views
Overlapping map tiles with mapnik's generate_tiles.py script
I'm trying to generate map tiles using the mapnik's generate_tiles.py script, but the resulting tiles are overlapped.
Example
The tiles have the following directory structure: ...
4
votes
2answers
238 views
How to efficiently project datasets of varying coordinate systems into one coordinate system?
I am working on streamlining data processing at my organization. Currently we are using various large-scale Models that we will gradually bring into Python.
The gist of our data processing is as ...
8
votes
2answers
311 views
What happens to a feature class when importing to a feature dataset?
I am creating a model that needs to ensure that all input datasets end up in the same coordinate system (among other things). I was originally going to batch project all of the datasets whether they ...
0
votes
1answer
360 views
Choosing best projection/SRID
I created a shape in OpenJump and exported it to shape(ESRI) file and then imported it to SQL2008 via shape2sql ,
the problem is that it shows bigger than what I want,
In OpenJump it shows 1meter ...
1
vote
0answers
336 views
mixing lon/lat and mercator layers in a MapServer .map file
I have a basic question about my MapServer .map file, which has two layers, each with a different coordinate system, longlat vs. mercator.
See my .map file below. If I leave it as shown below, with ...
27
votes
2answers
805 views
What projection appeared in the NYTimes this morning?
Perhaps not as GIS related as some, but definitely about maps.
Can anyone identify the map projection that appeared in the New York Times this morning? It's not one I've seen before, and a quick ...
1
vote
0answers
81 views
List of methods of determining the projection of a shapefile when .prj is missing [duplicate]
Possible Duplicate:
Best practices for identifying the unknown coordinate system of a Shapefile
It would be helpful to mention what information is needed to perform each technique. What are ...
4
votes
2answers
687 views
TileCache and Openlayers Problem - Projections?
I have a very known problem, but I can't solve it.
I have set the same maxExtents in the config as in the Openlayers init JS. I have done the same thing with the projection (EPSG:900913) and done all ...
9
votes
2answers
353 views
Is there a way to draw a straight line on a map which also represents a straight line on the earth surface?
I'm trying to understand more on projections.
In this example, why must one calculate the curvature of the earth (great circle) if the map is already projected? Is there a way to draw a visibly ...
