A map projection is any method of representing the surface of a sphere or other three-dimensional body on a plane
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0answers
8 views
TileStache + Mapnik - Tiles are rendered randomly
I newly turned to TileStache to render Mapnik tiles because of the caching option. Before, I was using Mapnik python bindings only and it was working perfectly. Now that I use TileStache, the tiles ...
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1answer
21 views
OGR Projection transformation error
I am trying to convert shapefile that was created by FME in EPSG:900913 to EPSG:3857 (I know its the same definition) with OGR in a script.
datasource = ogr.Open(os.path.join(dirname,shapefileName))
...
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1answer
38 views
How to transform World data from EPSG 4326 to EPSG 3857
I have tryed different opensource tools to transform a world data shapefile from 4326 to 3857 but I always have an error. Im not sure, but is it because of Antartica?
I have tryed with GDAL and QGIS ...
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2answers
24 views
How to scale/reduce my polygon without changing the central lat & long?
I am writing a VBA code to resize my polygon, I get a input as vector points(Shape file). The code below resizes it as according to my scale factor but my central latitude and longitude are also ...
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0answers
36 views
How to find out what projection my data is using?
I have a set of data that I created from gps locations of images. The locations are in decimal. I don't know what projection was used when the data was captured.
I used QGIS to display the data with a ...
1
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1answer
21 views
Pseudo Mercator error?
I'm mapping on QGIS, I have a vector layer and his CRS is on EPSG:4326 - WGS 84, but also I wanted to put a satellite image, so when I do it, the image use WGS 84 / Pseudo Mercator.
The problem is, ...
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0answers
26 views
need info on GeoTIFF projection keys
I am a programmer (not a cartographer!!) developing an application which needs to read and write GeoTIFF files. I have a number of questions about those GeoTIFF keys which are related to projections.
...
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1answer
19 views
Editor and projections ArcGIS
When opening an edit session Arc is telling me that some of my shape files' coordinate systems do not match the data frame.
Here is the data frame coordinate system:
Stereo_70
Projection: ...
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4answers
62 views
What projection to use in ArcMap for a map that extends over Wgs84 Utm31 and 32
Please i have a Wgs84 Utm map that extends over 2 utm zones(31N and 32N). Using either of them distorts my map and ArcGIs allows you to choose only one projection per map. Please what can i do? Thank ...
1
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2answers
47 views
Mapping elements in a warehouse
I am new to GIS. For a small project I want to map elements in a warehouse and want to find the location of the elements later (e.g. nails are located at x,y).
Now I am wondering what kind of ...
1
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1answer
57 views
How to create a Winkel-Tripel map of countries with different colors?
I need a good quality rasterized world map, Winkel-Tripel projection, in which all countries have different (random?) colors. No borders, text, grid or anything else on the map.
Is GIS the right way ...
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1answer
26 views
If I've given two different layers the same CRS, why won't they overlay one another?
I have a "towns" and "state" shapefile for Massachusetts as two separate vector layers in QGIS. I've set the project coordinate system to WGS 84 at the bottom of the screen (next to the "coordinate" ...
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1answer
48 views
Why does map display like it is in Isometric when everything is in EPSG:4326?
I'm beginning with Geoserver and try to display a map of my country (Belgium) is an openlayer map (embedded into a MapPanel object). I've downloaded the municipalities limits from gadm.org and copied ...
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1answer
53 views
Some terms related to coordinate
I was googling coordinate related information all the day. Now I am confused with some concepts and terms. I hope some one can help me to make it clear.
Geographic coordinate system
Geographic ...
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1answer
36 views
When is a projected length calculated via a pythagorean distance more accurate than an ellipsoidal length?
I'm using spatialite 3.0.1 with the following test data (in EPSG: 4326):
Name astext(geometry)
---------- --------------------
Belitsa POINT(23.563 41.947)
Malko Tarn POINT(27.533 ...
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0answers
32 views
what is the difference between the Geographic coordinate, transformed coordinate and screen coordinate [duplicate]
What is the difference between the Geographic coordinate, transformed coordinate(projected) ,cartesian coordinate, and screen coordinate? Is there a live example?
And what is the association between ...
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2answers
44 views
Thiessen Polygons and Coordinate Projections
I am trying to perform a Thiessen Polygons analysis in ArcGIS 10.
My DEM is in GGRS_1987 and the point set I downloaded from Google Earth is in WGS_1984. The points display correctly but when I run ...
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1answer
32 views
Wrong object size after projecting spatial data from one coordinate system to another
I am having problems reprojecting items in ArcMap 10.1 from British National Grid To WGS84. (WKID: 27700 Authority: EPSG to WKID: 102100 Authority: ESRI)
All Polygon Layers I project [I use Project ...
2
votes
3answers
139 views
Which CRS to use for Google Maps?
I am trying to map a Shapefile (download) onto a Google Map using the Javascript API. The Shapefile describes the boundaries of NYC School Districts.
The file's projection was Lambert Conformal ...
1
vote
1answer
32 views
Is it possible to have another CRS in the status bar than used for the map?
I am new to QGIS.
When I use OSM or Google Maps as a basemap via Open Layer Plugin, the map should be projected as EPSG: 900913. However, the Coordinates shown in the status bar are useless for me, ...
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2answers
69 views
Tile script (Mapnik) with OpenLayers - Problem with projection (900913)
I use Mapnik python bindings in a geodjango application to render tiles in openlayers with datasource stored in postGIS in 900913 projection. The feature seems to be rendered correctly in the ...
2
votes
1answer
60 views
Blank MapServer WMS image at low zoom levels in OpenLayers
I have an OpenLayers map using OSM as the baselayer with several layers coming from MapServer via WMS. The OL map is in EPSG:3857 and my mapfile (and shapefiles) are in EPSG:4326. In my mapfile I ...
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1answer
56 views
how to make the translation between latitude/longitude and screen pixels
The earth is three dimension object while our screen is two-dimension.
So when we use the gis software to display the geographic data, how do they handle the translation between latitude/longitude ...
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0answers
53 views
Using gdal to convert from UTM to equidistant lat/lon
I am getting rather confused with converting a UTM gridded dataset into a equidistant/rectangular latlon gridded dataset. Can anybody help me?
I have a UTM set with the following projection:
...
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1answer
58 views
Problem Overlaying layers in OpenLayers
I have a html page with 2 WMS layers.
The first is one Base Layer , & the second is my personal WMS feature. I load it from Geoserver. The problem when I add the 2 layers I do not have the ...
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 ...
1
vote
1answer
55 views
Why do points shift when reprojected from WGS84 to a state plane coordinate?
We have a Trimble unit we use to collect equipment.
We collect the data in WGS84 and differentially correct it and then reproject it to a state plan coordinate system.
The points always shift the ...
1
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0answers
59 views
QGIS: Different projection result for on the fly and transformation
I am a bit confused about the result of a re-projection/transformation of a raster in QGIS 1.8 (Lisboa).
WGS84 to WGS84/UTM34N. When I use the 'on the fly' transformation the resulting raster has a ...
0
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0answers
19 views
De facto QGIS projection for EPSG4326 / 'unprojected' reference systems? [duplicate]
This is my understanding of projections/datums:
To get a map of the earth on a plane you need to project the 3 dimensional earth by 'wrapping' a plane around it in the way that suits you (according ...
2
votes
1answer
39 views
Do FeatureLayers reproject their features to adapt them to the map projection?
I'm working with the ArcGIS Flex API.
For example, ArcGISDynamicMapLayers do reproject their data in order to make it in the same projection as the map.
Do FeatureLayers have the same behaviour?
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0answers
24 views
QGIS: Unable to project raster layers correctly on a Toshiba Tecra 64# Win7
I know how to project a raster, I can do it on other machines. On this particular machine the raster loads but are no where near the correct position as if the datum is on another planet.
11
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1answer
103 views
Assign projection to a satellite image
Today I stumbled upon a picture taken from the ISS looking down Europe and it is really beautiful.
So, I started thinking I could add more to the picture. Like world borders, cities, road network, ...
1
vote
2answers
48 views
define a datum and meridian in a CRS in QGIS
I have a shapefile defined by the source as:
"The layer is in geographical (lat-long) coordinates (GCS_Clarke_1866; Datum: D_Clarke_1866; Prime Meridian: 0)."
opening the shapefile in QGIS 1.8 the ...
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vote
1answer
49 views
Incorrectly Projected PostGIS data in TileMill
When I bring PostGIS data in EPSG:900913 into TileMill, my layers end up on other continents.
This is my workflow:
(1) Save shapefiles in QGIS to EPSG:900913
(2) Import the shapefiles using PostGIS ...
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votes
1answer
41 views
Wrong projection on WFS layer with OSM baselayer [duplicate]
I am trying to add a vector layer with a WFS protocol.
var wfs = new OpenLayers.Layer.Vector("WFS", {
strategies: [new OpenLayers.Strategy.BBOX({resFactor: 1})],
...
2
votes
1answer
157 views
What are the units of the calculated area from a raster in decimal degree
I'm trying to calculate area for a raster file which contains 2 layers (0 for unsuitable habitat and 1 for suitable). It's been calculated successfully but I don't know what is the unit of the ...
1
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0answers
28 views
how to get correct geo reference system for a VMap
I am new to GIS, trying to read the GeoRef System for VMap by using the following code:
OGRSpatialReference *ref = layer->GetSpatialRef();
if( ref )
{
QString georefSystem = ...
1
vote
0answers
21 views
Projection issue: mismatching .shp even if with the same SCR [closed]
I have a problem with some .shp from ARCgis (point and polygone) that appear on QGIS with mismatching SRC. When I change and save the new SRC (even by doing "save as") to make them match nothing ...
12
votes
2answers
206 views
What is the approximate error of the Pythagorean Theorem vs. Haversine Formula in measuring distances on a sphere at various scales?
Many people when first trying to calculate distances between two longitude / latitude pairs ask if Pythagorean theorem works as an appropriate distance function.
Most often people answer "no, the ...
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0answers
43 views
How to get Earth radius in pixels?
I need Earth radius in pixels for use in Mercator projection. Well let's say that our map's height is 1478 pixels and distance between 0 pixel and 1478 pixel is 2.52 degree. Radius is distance from ...
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 ...
1
vote
1answer
87 views
openlayers multiple layers with different projection
My page contains two layers: 1. Open Street Map as a basic layer and WMS layer from mapserver as a overlay layer. My map show this two layers but in a wrong position. I spent a lot of time trying ...
3
votes
1answer
58 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 ...
6
votes
2answers
93 views
IDW spatial interpolation: appropriate projection?
I am wondering if anyone can clarify whether point data should be projected to an equidistant projection when using ArcGIS IDW spatial interpolation?
I am working on a dataset from Western North ...
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votes
1answer
60 views
OpenLayers WMS - TypeError: this.resolutions is undefined
I'm trying to setup a map with WMS and WFS Layers by using Geoserver.
However, when I'm combining WFS and WMS (with some Google basemaps) together in one map I got following error in Firebug:
...
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0answers
40 views
I want to change EPSG:4326 to EPSG:900913 using C# for a set of uploaded shapefiles
I have written some code (using help from these pages) that uploads a directory full of shapefiles to a geoserver using C#. The uploaded shapefiles are set to EPSG:4326 however I would like them to be ...
0
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0answers
44 views
Reprojecting raster data from a rotated pole grid
I have some raster data (ASCII grid files) that use a custom rotated-pole projection, that I'd like to reproject into something more useful, such as lon/lat WGS84. A description of the grid projection ...
0
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2answers
67 views
WFS reprojection problems
In geoserver i have a layer in EPSG:4326.
In OpenLayers i add it on map as WFS:
markerLayer = new OpenLayers.Layer.Vector('Markers',{
strategies: [new OpenLayers.Strategy.BBOX()],
...
0
votes
1answer
42 views
Imported GPS data does not overlap with map
I´m working on QGIS and I geocoded 2 addresses of a city in Germany and tried to input the text-file as a layer. It worked, but the 2 points must be in the map of the city and if I zoom to the ...
2
votes
1answer
45 views
Transformation of user-defined projected coordinatesystems
I want to transform from one projected coordinate system (pcs) to another using ArcGIS 10. Unfortunatelly the starting system is not predefind by ESRI and thus I´m not sure the software is doing what ...
