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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302 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
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1answer
320 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
883 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
254 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 ...
6
votes
6answers
1k 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
369 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
1k 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
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2answers
839 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
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2answers
5k 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
15k 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
957 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 ...
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4answers
777 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 ...
2
votes
4answers
1k views

Can Civil 3D reproject shapefiles? [closed]

Sorry to ask, but I just don't have time for help menus this week. That said, does anyone know if CAD is capable of re-projecting shapefiles? I find myself in a situation whereby I may have to use ...
7
votes
5answers
10k 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
1k 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
929 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
16k views

Calculating projected area of polygons with field calculator in ArcMap?

I've got a polygon featurelayer in ArcMap 10. 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
4k 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 ...
11
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10answers
11k 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
955 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
4answers
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 realistic....
22
votes
1answer
5k 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 (...
48
votes
11answers
22k 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?
11
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" (http://vis.stanford.edu/protovis/ex/...
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 ...
26
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6answers
13k 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 ...
10
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
333 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
839 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 ...
5
votes
2answers
360 views

Does the Chamberlin trimetric projection map (some) great circles to straight lines?

I know that, in general, the Chamberlin trimetric projection maps most great circles on the sphere to some sort of non-straight curve on the flat map. But what about the 3 special great circles that ...
45
votes
6answers
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Why is the 'straight line' path across continent so curved?

This is the result of mapping the straight line path from a point in US to Poland using Distance Measurement Tool. Also, planes from Asia to US would travel almost over North Pole. Why is the path ...
4
votes
1answer
321 views

Using projections to obtain perspective views

I understand that a perspective view is essentially a type of projection. Is it possible to create projection definitions for a typical GIS system that will mimic a perspective view from a particular ...
2
votes
2answers
1k views

albers projection to Lat, Lon

Thanks in advance for helping me with my issue. This GIS stuff is using parts of my brain that have remained idle since high school, and some parts are working faster than others. I have land data ...
5
votes
1answer
4k views

Converting Lambert Conformal Conic to WGS84 using Proj.4

I am attempting to transform data from Lambert Conformal Conic lat/long and I am having some issues with the results. The shapefile I am attemtping to transform can be found here: http://tfr.faa.gov/...
5
votes
1answer
674 views

How can I specify a PROJ.4 projection with the north pointing *down*?

I would like to create a world map "upside down", with the south on top (in Mapnik). Can I take an existing projection string, e.g. Robinson projection +proj=robin +lon_0=0 +x_0=0 +y_0=0 +ellps=...
8
votes
1answer
785 views

QGIS- “On the fly” projection ON by default?

In QGIS 1.6, can users set "on the fly projection" to be checked ON by default (at application launch)? I know how to turn it on, but some users find they use it more often than not, and would like ...
3
votes
1answer
2k views

OpenLayers doesn't show an overlay with a different SRS than the base layer

I need to add an overlay layer that uses EPSG:4326 to a map with a base layer that uses EPSG:32628. Every time I add the overlay OpenLayers automatically switches the SRS param of the overlay to EPSG:...
8
votes
3answers
859 views

What kinds of line segments/edges require high accuracy in a true surface-of-the-ellipsoid representation?

I've been musing (and doing prototype coding) for a 'projection free' geographic codebase with your basic point, line & polygon primitives. Rather than dealing with all the sacrifices that come ...
6
votes
2answers
8k views

Basic proj4 conversion UTM grid -> longlat and back

I'm a GIS novice, and am struggling to understand how to drive proj4 to accomplish what seems like a simple thing. I've googled for a couple of days, but everything I find seems to presuppose quite ...
10
votes
3answers
2k views

What is the right solution (and map projection) to compute distances between points located all over the World?

After my study on map projection I realized that it is very difficult to choose a projection that allows to compute simultaneously the distances between a great deal of points if these points are ...
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vote
2answers
634 views

How to add new projection using ArcObjects of ArcGIS for Desktop?

I want to use "Mars MOLA" { 86 3396000.0 3396000.0 "Mars MOLA" 0 0 0 0 0 0 0 } with my shapefiles.
2
votes
2answers
2k views

Converting google map api coordinates into meters

How would I go about converting the results of my map bounding box into meters within javascript? For example, if I have the coordinates 51.52366625446907, -0.07467269897460938 decimal degrees, can I ...
8
votes
2answers
1k views

How do I rotate the OSM map before printing?

What is the simplest way to rotate and render Openstreetmap data, and still get a nice render? For example Toronto, would fit best rotated slightly on a page in landscape mode, so the northern ...
4
votes
1answer
501 views

No difference between distances measured in projected and non-projected data

I'm performing measurements of distances in Km between a lot of localities by using the "Point Distance" in ArcGis 9.3. I realized that the results obtained after using projected coordinate system are ...
26
votes
1answer
4k views

How to create an accurate Tissot Indicatrix?

A Tissot Indicatrix is useful method for communicating at a glance the kinds of distortion a given projection is prone to (in the figure below, each of the red circles occupies the same area). I've ...
23
votes
6answers
19k views

Defining projections for multiple shapefiles in ArcMap?

I have over 100 shape files that don't have .prj file and thus when I bring them into ArcMap 10 they show the coordinate system as unknown. I know all of the shape files coordinate system is GCS WGS ...
9
votes
4answers
842 views

World map projection with United States in center

I am creating a map showing flight paths originating in the United States and traveling to Asia and Europe. I need a projection for the world that will focus the United States in the center of the map,...
3
votes
1answer
1k views

Conversion of any projection to latlong using proj4 string

I am using a tool which uses proj4 lib to project maps. I have a set of xy coordinates to be converted to latlongs with that tool. as I have the source projection string say +proj=aea +datum=NAD83 +...
8
votes
6answers
2k views

Real-world example of Affine Transform?

From the Wikipedia article: In geometry, an affine transformation or affine map or an affinity (from the Latin, affinis, "connected with") between two vector spaces (strictly speaking, two affine ...
5
votes
1answer
2k views

Projected maps should but do not overlap in ArcMap? [duplicate]

I am very new to ArcGIS and trying to build a series of layers of data in ArcGIS 9.3.1 for a river catchment in Leicestershire, using data from several sources. All data covers at least the area of ...