A map projection is any method of representing the surface of a sphere or other three-dimensional body on a plane
0
votes
2answers
60 views
How do I reproject one raster to match another's in GRASS
I have two raster layers, A and B, which have information about the same location but have different projections and datums.
How can I reproject layer A to match the projection and datum of layer B?
...
0
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})],
...
1
vote
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 = ...
11
votes
5answers
3k views
How can I measure area from geographic coordinates?
If I have polygons in geographic coordinates (WGS84), how do I measure the total area each takes on the surface of the earth, taking into account the curvature of the earth?
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 ...
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 ...
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 ...
0
votes
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 ...
15
votes
5answers
5k views
Map projection in OpenLayers
I want to overlay some data whose projection is WGS-84 on Google map layer in OpenLayers. But I just can't make them in the right place. I did as follows:
map = new OpenLayers.Map('map', {
...
1
vote
1answer
89 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 ...
9
votes
2answers
244 views
How do I perform a 3 parameter geotransformation and projection in Sql Server 2012?
I have a table with latitude longitude (NAD27) columns in it. I compute two other columns, X and Y, representing Web Mercator (WGS84) location.
Currently I'm using a Arcmap to do this, by applying ...
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 ...
0
votes
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 ...
7
votes
1answer
93 views
Which training courses in Geodetics can you recommend?
Can anyone recommend any training courses in geodesy which would cover the following objectives:
Case studies on coordinate issues
Overview of geodetic datums, coordinate reference systems and ...
0
votes
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
votes
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
44 views
Ok to measure and union a projected-on-the-fly shapefile in ArcMap?
I have a dataframe in arcMap 10.0.4 that is of Africa Albers Equal Area Conic PCS. I bring in a census shapefile of WGS 1984 CS and it is projected on the fly.
I do 2 things:
I use the calculate ...
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 ...
0
votes
2answers
64 views
Getting a “square” of lat/lon for database query [duplicate]
So I want to get the square formed by a single point of lat/lons, my plan was to take that point's latitude, divide by 360, and multiply by the circumference of earth. Giving us the distance from the ...
1
vote
1answer
28 views
Setting coordinate systems in gvSIG: workflow or transformation issues
I am learning how to use gvSIG 1.10 (Mac OS 10.6.8 Snow Leopard). My goal is to create a simple county map of Illinois using the base data shapefiles available from the Illinois Natural Resources ...
5
votes
3answers
647 views
Using arcpy what is the most efficient way of projecting a selection from a large data set?
I have a large data set X(x1-xn) from which I must select consecutively the attributes A(a1-an) from X.fieldsSRC or X.fieldDST and project the selections.
I have a functioning arcpy script that does ...
0
votes
0answers
42 views
How to join edge of International Date Line in world file?
I am currently using world file (http://www.ngdc.noaa.gov/mgg/shorelines/gshhs.html) for international boundary information.
Now I have difficulty with map projection that the map ends with ...
1
vote
3answers
43 views
Trying to match delimited text layer to my shapefile
I'm pretty new to QGIS and having a bit of trouble getting a text layer to match my shapefile. I'm trying to plot Canadian cities on a shapefile I have of Canada provinces.
The provinces shapefile is ...
0
votes
0answers
53 views
Shapefiles with EPSG 31467 and 3044 don't fit together [closed]
I have a problem with some shapefiles I want to fit in my exisiting project. My project layers use as CRS EPSG 3044. They do fit together with OpenLayers GE (EPSG 3857). Now I wanted to add some new ...
1
vote
1answer
69 views
Data points Imported into QGIS are in the middle of ocean
I'm new to QGIS and tried importing some GTFS data in the CSV format (stops.txt). The project CRS, base map CRS and GTFS CRS have all been set to Google Mercator, but the points that are supposed to ...
1
vote
2answers
79 views
Get Lon Lat values from a GEOGRAPHY data type in PostGIS
After storing lon lat values as a GEOGRAPHY data type, how do I retrieve the individual lat lon values?
Failed attempt:
SELECT id, geog, ST_X(geog), ST_Y(geog) FROM locations;
Error:
No function ...
1
vote
0answers
36 views
Determining the SRID of a dataset in PostGIS [duplicate]
Sometimes the dataset provides some information about its projection. For example, it can mention Horizontal_Datum_Name: North American Datum of 1983, Ellipsoid_Name: GRS1980, ...
1
vote
2answers
160 views
What Spatial Reference System do I store Google Map's Lat/Lng in
I am new to PostGIS, Spatial Reference Systems and projections and want to store lat/lng coordinates retrieved from Google Maps and Openstreetmap and its services like the Geocoder/Nominatim. I'm ...
2
votes
2answers
65 views
What's the correct transformation for Lambert Conformal Conic for Wyoming?
I am a newb in QGIS. I have loaded QGIS 1.8 (Lisboa) and practicing with a number of maps for portions of the state of Wyoming. My maps are mostly in UTM 12N NAD 27 & NAD 83 some are in decimal ...
3
votes
1answer
72 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, ...
0
votes
0answers
43 views
include the robinson projection into open layers
I need to include a robinson projection into openlayers, but i found no epsg code for it.
i have this spherical mercator projection at the moment and need to change it, but i dont know if it is ...
2
votes
1answer
102 views
Correct coordinate systems, but trustworthy distance between points?
I have limited GIS experience with projections and I have some questions about trying to accurately display point data from two different sources in ArcGIS 10.1 in order to do a proximity analysis.
...
2
votes
0answers
22 views
Projection string for GOES-WEST
Full-res, full-disk GOES-WEST images are available from
goes.gsfc.nasa.gov. Is it possible to rig up a projection
string for these images?
We know the center pixel is at (0N, 135W) and the
satellite ...
2
votes
1answer
110 views
QPJ files on ESRI software
We have some GIS data, which was converted from AutoCAD dwg to TAB using mapinfo, then converted to shapefiles as that's what we are required to create. Editing the data fields was done in the shape ...
0
votes
3answers
265 views
How can I get the proj4 string or EPSG code from a shapefile .prj file?
I have to work with a shapefile defined in an unusual projection, which my GIS software does not know about. How can I get the proj4 definition or the EPSG code for the projection?
0
votes
0answers
15 views
How to use Mercator projection on png map [duplicate]
I´ve got map(png) with size 2143x1723. When i want to get WGS84 coordinates to each point i use following algorithm
for (int i = 0; i < pictureBox.Image.Height; i++)
{
// ...
3
votes
1answer
58 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 ...
1
vote
2answers
68 views
Layers with same coordinates not lining up [QGIS]
I have a project where I have a few layers (State of Texas, cities, roads, etc.). They are all resaved and projected to NAD83 / UTM zone 14N EPSG: 26914. The project CRS is also NAD83 / UTM zone 14N ...
1
vote
0answers
43 views
How to import multiple shapefiles each with different source projections to postgis
I have a couple thousand .zip files each with a .shp, .dbf, .shx, and .prj inside them that I want to load into postgis. The problem is, they have many different source projections (each defined in ...
0
votes
0answers
79 views
Reprojecting coordinates and geoJSON in leaflet
I have a Leaflet map in default projection and a wms layer also in default (web mercator) projection. I would like to add polylines and a geoJSON layer to my map, but the coordinates are in EPSG4326. ...
1
vote
2answers
61 views
problem about reprojection
I am a new GIS user, I have some problem can not be solved by myself. I get a shape file generated from an Excel file. at first, my projection is WGS_1984_UTM_Zone_48N some data are inside my country ...
2
votes
1answer
54 views
How to bulk import ESRI projections into Postgis
Where can I get a file that would allow me to bulk upload all of the ESRI projections into the spatial_ref_sys table of postgis. I know that you can get insert statements on spatialreference.org; ...
2
votes
1answer
53 views
Which BC Albers should I use and is there any difference?
I was about to calculate the area of some polygons and before I did I did some research. I found that the area of the polygon will be represented in the units of the projection used. So I did some ...
0
votes
1answer
60 views
constant deviation projecting lat lon to itm(israel tranverse mercator
i use two different ways to project lat lon data taken from google earth to ITM (Israel Transverse Mercator) and export the data to arcmap same ways i try to unproject ITM data and export the data to ...
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 ...
3
votes
2answers
144 views
Converting lat lon into co-ordinates (in ft of m)
I have a set of latitude and longitude of a series of points which specific the trajectory of a vehicle.
If I consider the first point as the origin (0,0), is it possible to convert the trajectory ...
1
vote
1answer
71 views
Projection WGS 84 is slightly displaced referring to a hillshade in QGIS
I have a hillshade and a vector layer. The vector layer is slightly displaced referring the hillshade. About lat=100m and long=175m
The CRS of the project is EPSG:3397 - PD/83 / Gauss-Kruger zone 4.
...
2
votes
2answers
117 views
Cartesian world sized projection WKT/EPSG code?
I am after the EPSG code or Well Known Text (WKT) of a projection that puts the centre of the earth a 0,0,0 and each point is a cartesian XYZ distance from that.
My existing data is in WGS84 ...
