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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517 views

How to Extract Data from U.S. National Landcover Dataset (NLCD) dataset?

I am working with U.S. National Landcover Dataset (NLCD) to classify habitat type at more than 150 sites across the northeast U.S. The dataset is very large (15GB) so I cannot upload it here, but it ...
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107 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 ...
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649 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 ...
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1answer
113 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 ...
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132 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 ...
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447 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 ...
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1answer
897 views

Find projection of a point to a line

I have a segment defined by 2 LatLon points(A and B) and a third LatLon point (C). I need an alghorithm, formulae, or some code to find the projection point of C on the segment AB (call this point D) ...
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3answers
97 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 ...
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181 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 ...
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2answers
546 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 ...
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3answers
5k 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 ...
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39 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, ...
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2answers
3k 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 ...
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1answer
405 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, ...
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2answers
530 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 ...
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1answer
670 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. ...
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2answers
744 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? ...
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2answers
3k 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 ...
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59 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 ...
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4answers
410 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 ...
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3answers
13k views

How can I get the proj4 string or EPSG code from a shapefile .prj file? [duplicate]

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?
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1answer
595 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 ...
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101 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 ...
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1answer
1k 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. ...
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1answer
349 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 ...
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2answers
3k views

Layers with same coordinates not lining up

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 ...
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1k 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 ...
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2answers
69 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 ...
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1answer
515 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 ...
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275 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 ...
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187 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; ...
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1answer
166 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. ...
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2answers
2k 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 ...
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1answer
129 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 ...
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1answer
890 views

ArcGIS Desktop, shapefile 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 ...
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0answers
74 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 ...
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1answer
168 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 ...
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1answer
210 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 ...
4
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237 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 ...
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75 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
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1answer
321 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 ...
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3answers
403 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 ...
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1answer
112 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
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1answer
186 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 ...
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0answers
745 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,
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1answer
121 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) ...
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2answers
633 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
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1answer
244 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 ...
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1answer
163 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 ...
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1answer
1k 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 ...