A map projection is any method of representing the surface of a sphere or other three-dimensional body on a plane

learn more… | top users | synonyms (1)

6
votes
4answers
10k views

How to reproject base layers in OpenLayers?

The issue is: I have vector/topo/image tiled maps for some places in north america which were published as ArcGIS Server REST service. These maps (A) are based in EPSG26912 projection. Now I wanna ...
0
votes
2answers
1k views

How would I convert this point to WKID 4326?

This is a point in Brewster, MA, USA. How would it be converted to WKID 4326? 324299.3348436486, 832511.5939650714
4
votes
2answers
2k views

How to “calculate” distance-to-ground of all 18 OSM zoom levels?

Assuming I'm building a 3D solution with the "world" being mapped to global geo-data supplied by OSM / Cloudmade... think http://www.webglearth.com but with completely different goals and use-cases. ...
3
votes
2answers
251 views

What projection is this in GDAL classification

I need to re-project a PNG from a given projection to the Google maps projection. I have a grid of the source projection, looks like a Mercator projection. What is the exact name of this projection in ...
2
votes
1answer
689 views

Rendering 3D timezones KML on a 2D map

I'm trying to render a KML layer (with timezones) in Google Maps API v3. The KML layer works fine in 3D (in Google Earth), but when I render it in 2D, the timezone lines that meet at the North Pole ...
41
votes
4answers
7k views

Why has Web Mercator (auxiliary sphere) become the web map standard?

I understand what the difference is between the Web Mercator projection and Web Mercator Auxiliary Sphere (WMAS). I also understand that both Google and Esri have adopted this projection as their ...
0
votes
2answers
279 views

Shp's will NOT line up (coordsys) - shps made using GPSeismic sotftware (client made shp's)

OK, I asked this previously but solved it on my own last time. Same project, but differant shp files. I recieved from a client shp files that were made in GPSeismic 2011. Upon recieving the shp ...
2
votes
1answer
86 views

Coords not aligning

The two shp files are not aligning like they should (note the img). The layer and the two shps all have the same coords - NAD_1983_StatePlane_North_Dakota_North_FIPS_3301_Feet The surface shp came ...
1
vote
2answers
585 views

Project WGS84 to Google using MapGuide and WKT

I'm having trouble projecting a simple WGS84 formatted layer over google maps. I can't find a good WKT "API" that not only shows parameters, but explains what each parameter is. The coordinate system ...
6
votes
1answer
772 views

SRID error in mapserver

I've created a network topology using QGIS, saved it as a shp, imported it into PostGIS using shp2pgsql and I'm now trying to output some of the geometry using mapserver. Unfortunately mapserver is ...
3
votes
0answers
1k views

Converting projected coordinates to google maps pixels

I have a single polygon in a local projection system. I would like to convert that polygon into an image that can be used as an overlay on google maps. I understand that it may be better to use ...
0
votes
1answer
464 views

How to point out a city from a map image of world with longitude and latitude?

have a map image 800px wide. How can I figure out a city. like New York has 40.75 latitude and -73.98 longitude. I have to pin a mark over this point. Before I have done with x_axis and y_axis which ...
2
votes
2answers
508 views

Error when setting projection of a tif file in QGIS. Any ideas to solve this? [closed]

I get this error when trying to define a projection for a tif file in QGIS: ERROR 1: Too many points (3249 out of 3249) failed to transform, unable to compute output bounds. How do i work this out? ...
1
vote
1answer
496 views

How to resize layer using .prj (WKT) projection? (Geographic Coordinate System)

Briefly: How to parametrize .prj WKT file so that I can perform 7 point tranformation (wiki). I know how false_easting and false_northing params work, but how can I adjust scale? I do not mean ...
2
votes
2answers
404 views

Shapefile CRS changed after exporting from QGIS. Are they equivalent?

I added a shapefile as a vector layer in qGIS 1.7 so that I could join in additional attribute data (not geodata) from another DBF file. The Shapefile that I added has this CRS (as far as I can tell ...
2
votes
4answers
4k views

Export to new projection in QGIS 1.7

Suppose I have layers A and B. I don't know their projections but by the looks of the map I know they are not the same. In QGIS 1.6 I would use one of my favorite features: Vector> Data ...
4
votes
4answers
638 views

Determine Projection

I was given a shapefile at work with the information that it is in Lambert Azimuth Equal Area (LAEA) projection (EPSG 9820). After some research on the web, I found out that EPSG 9820 is a generic ...
12
votes
1answer
590 views

How is a “conformal latitude” used in ellipsoidal stereographic projections?

At my work, I've been doing some maintenance on internal software that claims to implement a Stereographic projection whose formulas were copied from an old system a long time ago. From what I've ...
0
votes
2answers
262 views

How to realign misplaced GeoTiffs?

I have bought a few (30) GeoTiff maps from my country's Geo-department - South Africa. They all have a date in the filename and the newest one was created in 2004, I see one is dated 1977 - that old! ...
1
vote
1answer
355 views

Defining custom projection for moving all objects on X and Y coordinates

I have a map project wih layers in WGS1984 UTM projection. I also have a bunch of layers without .prj files. When I add it on top of my layers, it's placed with a huge offset on X and Y coordinates ...
3
votes
1answer
1k views

Mapserver, TMS, Scales zoom levels and how to deal with all of it

I have a whole bunch of data in my db that I need to draw at different zoom levels using Mapserver. Everything uses a 4326 SRID. My (custom) client, will fetch the data using 20 TMS zoom levels and ...
2
votes
2answers
2k views

Problem reprojecting data from personal geodatabase using QGIS

I have a dataset in the form of a personal geodatabase (mdb) and am interested in using certain feature classes for further processing. My problem is - I am using USGS data orthoimagery which comes ...
5
votes
1answer
290 views

Mapserver tiles - trouble with projection

I'm trying to render tiles with shp2img tool from Mapserver suite and my tiles aren't matching. Tiles are numbered like in openstreetmaps.org. This is an attempt to draw tile (level 1, x=1, y=0) which ...
1
vote
1answer
306 views

How to reproject a noaa bsb nautical chart?

I have some nautical charts in .BSB format. GDAL can read bsb and I successfully imported them to qgis. But I can't figure out what is the coordinate system they use. Does anyone has some experience ...
3
votes
1answer
820 views

How to provide transform information to openlayers on Image layer

I would like to include an overlay raster layer into my OpenLayers map. I've pre-transformed the image into the correct projection (EPSG:900913) and saved as a png using the gdal_translate command: ...
4
votes
1answer
243 views

Access is Denied error on ProjectEx call

I need to be able to convert a lat/long coordinate into a point coordinate and am having trouble getting my code to work. I created a test app isloating the code that is giving me problems. I'm ...
5
votes
6answers
949 views

Southern hemisphere projections for Landsat upsets GRASS

Hi All does anyone have the last word on why Landsat scenes don't project in the southern hemisphere. This causes no end of trouble in GRASS, less so in QGIS. What I mean is, take an original scene ...
1
vote
1answer
356 views

How to project the result of a QueryTask in ArcGIS Javascript API?

I have created a web map that displays point features based on a given date range. Our current projection is Oregon State Plane South. My boss wants me to change the map to use a Web Mercator ...
2
votes
1answer
952 views

Geowebcache does not displaying map tiles in EPSG:900913 from a remote WMS server

I connect Geowebcache to a remote WMS service through their Getcapability request by adding the url in geowebcache-servlet.xml document. Geowebcache demo page displays the list of wms layers from ...
8
votes
2answers
618 views

Why are there both square and rectangle world maps?

When i search for images of earth divides to longitude ans latitudes seems that the are 2 major types: is a perfect square and the latitudes in it are grow a different rate from the equator to up ...
3
votes
2answers
4k views

How to read projection information from .dwg file

I have got an Audocad .dwg file which is based on some location of sweden. But i dont know what is the internal projection of this file? how i get projection information from this .dwg file. Actually ...
4
votes
4answers
11k views

Getting shapefile in right projection using ArcGIS Desktop? [duplicate]

I have an older map that I didn't create. I'm just trying to get everything to line up on it, and having a hard time. The data frame is in NAD_1927_UTM_Zone_12N, as are the point shapefiles (derived ...
3
votes
1answer
779 views

How can I programmatically project the Z value of a z-aware feature point, using ArcObjects in .NET/C#?

I discovered the following code leaves the Z coordinate of featurePt untouched: // if not WGS84 project it if (!SpatialRefsEqual(featureSpatialRef, srWgs84)) { // featurePt here is a Z-Aware ...
-3
votes
4answers
730 views

Repository for .prj files

Do you know any repository where can i find .prj files? I am looking for local coordinate system: Warszawa 75 (Warsaw 75) I found myself this repository but the .prj which i found there seems to be ...
7
votes
5answers
9k views

OpenLayers: ALL image layers are out of place on google maps v3 and OSM base layers

Summary: I have 2 different image layers that looked fine with my old mapstraction/google maps based system. Using the same coordinates as bounds in openlayers results in a shift to the north by like ...
4
votes
1answer
967 views

Matching ArcGIS and QGIS coordinate systems

I have the following info for a feature class in ArcGIS that is supposed to be in WGS 1984/UTM 16N projected coordinate system: Projection: Transverse_Mercator False_Easting: 500000.000000 ...
6
votes
2answers
815 views

What's a good toolchain to reproject some PNGs in plate carre to UTM?

I have some PNGs produced from Canadian DEM data. They're 1201px by 1201px heightmaps. Each one represents one quarter of a degree latitude and one quarter of a degree longitude. But I want to work ...
3
votes
3answers
13k views

Calculate projected area of polygons with field calculator in ArcMap 10

I've got a polygon featurelayer in arcmap. The coordinate system of the featurelayer's featureclass is web mercator. The dataframe of the map uses an equal-area projected coordinate system. I've ...
7
votes
2answers
3k views

what is the best way to programmatically convert between WKT and Proj4 string?

some shapefiles have a .prj file associated with it. and the .prj file contains the projection info of the shapefile in the format of WKT. Sometimes I need to convert WKT to proj4 string, and ...
10
votes
10answers
9k views

Batch convert lat longs to UTM?

I've got a .csv file that contains a long list of latitude and longitude points. Is there an efficient way to batch convert the list into a projected UTM coordinate system? Thanks.
10
votes
1answer
793 views

Error assessment of calculation done using unprojected vs. projected data

This question builds off of the one with the subject line "Calculating Flow Direction and Delineating Basins from Projected vs. Unprojected Data.": Calculating Flow Direction and Delineating Basins ...
0
votes
3answers
1k views

Distort image to Mercator Projection view

i have an image that rendered from data i have on my DB. i need to convert this image, with Mercator Projection method, to distorted image that when i'll wrap a 3d sphere with it it'll looks ...
19
votes
1answer
4k views

Calculating Flow Direction and Delineating Basins from Projected vs. Unprojected DEM Data

This is somewhat of a theoretical question stemming from some discussions with colleagues on the topic of implications with delineating basins with projected (e.g., Albers Equal Area) vs. unprojected ...
35
votes
11answers
15k views

Identifying Coordinate System of Shapefile when Unknown?

I have a Shapefile but its coordinate system is Unknown, and there is no *.prj file. How I can identify it now? Are there any tools that could help?
10
votes
2answers
2k views

What is the standard Mercator projection?

I'm using QGIS in order to re-project a shapefile I have into "Mercator" so that something like protoviz understands my co-ordinates. Protoviz tells me "Mercator" ...
3
votes
2answers
1k views

Setting the map projection in the flex API to an overlay layer

I'd like to use a basemap containing world map data as a backdrop to some point and outline data that I'm hosting in ArcGIS server in the ESRI Flex API, but I would like the map control to share a ...
23
votes
6answers
10k views

Shapefile PRJ to PostGIS SRID lookup table?

I was wondering if there is such a thing as an shapefile PRJ to PostGIS SRID lookup table? Something that can translate the most standard shapefile PRJ definitions into the likely SRID. When using ...
9
votes
2answers
3k views

Measuring distance in spherical Mercator vs zoned UTM

I've got points in WGS84 lat/long and I'd like to measure "small" (less than say 5km) distances between them. I can use the haversine formula from http://www.movable-type.co.uk/scripts/latlong.html ...
5
votes
1answer
319 views

Which projection casts rays from a point on the surface of the globe to a cylinder?

What is the name of a map projection that casts rays from a point on the surface of the globe to a cylinder? Some people who make sundials put a map of Earth on the sundial. I want to use the "right" ...
7
votes
2answers
768 views

Bertin 1953 map projection settings

I am trying to use the Bertin 1953 map projection, as described in the book "Semiology of graphics" by Jacques Bertin. But I can't find the settings in any of my GIS software. Does anybody have a ...