A map projection is any method of representing the surface of a sphere or other three-dimensional body on a plane
1
vote
2answers
76 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
157 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 ...
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, ...
2
votes
2answers
62 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 ...
0
votes
0answers
41 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
98 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.
...
0
votes
2answers
59 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?
...
2
votes
1answer
105 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 ...
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 ...
0
votes
4answers
151 views
Coordinates conversion doubt
In QGIS do I have a EPSG:4326 shapefile that shows the coordinates "-7148300 -3688500" and I need them in the format -64º -31º for further processing in a geodjango app.
However using ogrinfo I get ...
0
votes
3answers
247 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
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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
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 ...
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
74 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. ...
0
votes
0answers
71 views
Why do ArcGIS Area Calculations not match Official Statistics?
I am trying to calculate area of polygons using a shapefile from the world bank where countries are defined.
When however I am trying to calcuate the area, the numbers that emerge are different from ...
1
vote
2answers
63 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
1answer
67 views
MMQGIS: How to make grid layer in meters not degrees?
I've read several of the posts on here pertaining to MMQGIS Create Grid Layer option, but I have not found information on how to make the grid based on meters veres degrees. I know how to manipulate ...
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
52 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
59 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 ...
2
votes
1answer
52 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; ...
1
vote
1answer
68 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
110 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 ...
6
votes
1answer
74 views
Should I Reproject Data Which Has Been Captured Incorrectly?
I'm working on a project for a client which is migrating data from an Oracle database to an ESRI Geodatabase. When data for this project was initially captured over 15 years ago, the coordinate ...
0
votes
1answer
87 views
Arcgis shape file and EPSG code
Why a shape file with CRS WGS_1984_UTM_Zone_22N en Arcgis has a differrent prj file than the EPSG:32622:WGS 84 / UTM zone 22N WKT ?
Can I replace Arcgis .prj file with EPSG:32622 WKT
...
0
votes
0answers
28 views
export WebMap in a different projection than the WebApi
I am quite new to the Flex WebApi world. I am using the Flex WebApi and have set up map templates to print maps out to my own template as a PDF. In my template I have the Map grid set. When I eport ...
2
votes
1answer
41 views
CRS Austrian Lambert/WGS84
I am totally new to Qgis (or GIS in total):
My problem is to get two layers in same CRS to do an intersection and further analysis described in the blog of underdark (Groupstat tutorial).
My is the ...
7
votes
1answer
91 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 ...
2
votes
0answers
56 views
Proj4 inconsistent longitude after projection
All coordinates expressed in this question are (longitude, latitude), the default for proj4. London is at (-0.1460838, 51.5170986), and San Francisco is at (-122.419302, 37.775549). According to the ...
1
vote
0answers
45 views
Projection for Tracking a Vehicle
I'm looking for the best coordinate system projection to use for cartesian calculations while a vehicle is running from its starting location to about 100 miles from that spot.
The offline format ...
4
votes
1answer
64 views
Error in Min. Bounding Geometry results
I'm getting consistent, weird results from using Minimum Bounding Geometry to make circle polygons. I'm not sure if a datum issue, but I'm leaning more towards something wrong with Minimum Bounding ...
3
votes
3answers
150 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 ...
1
vote
1answer
26 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 ...
4
votes
1answer
48 views
Global projection with zero scale distortion at non-zero latitude
I am looking for a global projection with zero scale distortion at non-zero latitude.
I have tried using an Oblique Mercator projection centred at a specific latitude and longitude of centre (with ...
1
vote
0answers
75 views
Lines as Great circles on a map
How can I get line features to appear as great circles on a map, instead of straight lines?
Thanks,
2
votes
1answer
61 views
QGIS mixing up CRS
I´ve just started working with QuantumGIS for my thesis. I ordered shapefiles with the CRS: ETRS 89 UTM Zone 33N, but QGis layer properties now shows the layer has a different CRS (namely SWERE99 TM) ...
4
votes
2answers
146 views
Setting coordinate systems in gvSIG: Is the workflow similar to QGIS?
I am still learning how to use coordinate systems and projections, but I hope this basic question will be easy to answer. My goal is to be able to use either QGIS or gvSIG to create a simple county ...
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 ...
5
votes
1answer
105 views
What projection is this and how to use it in a GIS?
I have a request to do a map in non-standard projection:
(source: http://www4.agr.gc.ca/AAFC-AAC/display-afficher.do?id=1263246127905&lang=eng)
I couldn't manage to find it my materials. As well ...
8
votes
1answer
159 views
Great-circle lines in Equirectangular projection
Just to check that I'm on the right track:
Are all great-circles on the sphere and in equirectangular projection (i.e. latitude, longitude pairs) either:
meridians (i.e. going pole to pole)
of the ...
0
votes
1answer
70 views
How to get DXF to show up in the right spot?
I just followed the advice of this forum post in order to export the vector layers of a PDF for usage in ArcMap. The map vector layers in the PDF were spatially referenced. I was able to export the ...
5
votes
1answer
55 views
Having trouble finding out what coordinate system a map is using, and how to convert it
I'm using Small Area shapefiles in Ireland from the Central Statistics Office (CSO) website. The link to these is here http://census.cso.ie/censusasp/saps/boundaries/ED_SA%20Disclaimer1.htm (Look for ...
3
votes
0answers
187 views
VBA Convert decimal degree to Meters button
I have 2 data frames one which has WGS data in it and the other OSGB1936. I am trying to create a button where the user can input decimal degrees (WGS) and it will zoom them to that location in ...
1
vote
0answers
54 views
What is a radar projection?
Trying to overlay a radar image(radar projection) on a mercator projected map, but have no idea about what a radar projection is.
So here are my quesions:
What is a radar projection?
What's its ...
1
vote
0answers
98 views
What is UTM Zone 0?
I am currently working with some roadway link data and it is being projected in UTM.
After importing the shapefile into GRASS I can view the map and it looks correct but when I view the projection ...
1
vote
1answer
159 views
What are Bands, Dimensions, and Histograms in QGIS?
First; I can see a band as synonymous with a channel in an image editing program like GIMP, is this correct?
If so then bands play the role of color mixing and masking. Are there any other ...
2
votes
1answer
229 views
Which coordinate system and projection shall I use for georeferencing google map image in ArcGIS?
I have saved Google Maps image (not Google Earth) of area at latlon(17.692437,83.218689) by some method in jpeg format. It is an exact snapshot of the Google Maps. Now I need to geo-reference it to ...
0
votes
0answers
29 views
Need guidence about project [closed]
I am currently studying Remote Sensing and GIS. I previously completed a 4 year degree program in Mathematics.
I would like help in selecting my final thesis and a basic project work topic for the ...
