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)

0
votes
1answer
34 views

Determing which Which georeference system was used on an Ecuadorian Topo Baselayer

I'm creating a map in Western Ecuador, and am attempting to use a military topo baselayer for it. The map comes with UTM grid lines on it so georeferencing it was easy but I'm unsure of what ...
1
vote
2answers
195 views

Given a flight path given in latitudes and longitudes, how do I find another flight path that is parallel to the path given?

Given a flight route that is given in latitudes and longitudes, how do I find another route that is "parallel" to the route given (find a perpendicular line to each waypoint given)? I think the best ...
0
votes
1answer
35 views

Assign Projection to multiple shapefile

I have multiple shape files in a folder. I want to assign projection to all the files inside the folder at one go. In batch file i am able to assign projection to all the shapefiles, but i want to ...
1
vote
2answers
215 views

Why does Transverse Mercator projection have scale factor?

Why does the Transverse Mercator projection have a scale factor in ArcGIS and the standard Mercator projection not? In other words what is the difference between these two projections beside being a ...
0
votes
0answers
24 views

QGIS - unable to change projections [duplicate]

I am relatively new to QGIS (version! 2.0.1) and having trouble changing projections. No matter what I choose the view is the same. For example, in the attached screen shot I have chosen Alaska Albers ...
0
votes
0answers
61 views

Define Projection for an autocad transferred data

If I had a cadastral map on an Autocad file and i convert it to a dxf extension in order to open it in QGIS. I Added The Parcels borders and text in QGIS. Can you please list the steps which I should ...
1
vote
1answer
42 views

Equal (ish) areas Map Projection at the Tropics

What map projection (non-interrupted) preserves areas well for the entire tropical region? I am thinking of using a Cylindrical Equal Area or a sphere based version of a Cylindrical Equal Area or ...
3
votes
0answers
216 views

Convert land-based camera image pixel x,y to ground lat/long or x,y,z

I have a number of cameras at various known locations (x,y,z) and directions that are above ground about 20 feet pointed at different ground locations about 100 feet away from each camera, and whose ...
0
votes
1answer
85 views

How to find out projection code for the sid file?

I have a miami.sid file and miami.sdw and miami.sid.aux.xml files. How to find out the projection code? This question is similar to: I have a .sid image but can't figure out the CRS GDALInfo ...
1
vote
1answer
57 views

Using QGIS, features are suddenly placed 7.5 thousand kms off correct location

I've been counting an muskrat dens on lakes with aerial photos by creating a feature in a separate shapefile. I checked my progress after doing about 80 small lakes and suddenly, half of the lakes ...
2
votes
2answers
36 views

Comparing projections of two datasets when SRID not available

Similar to this question: How to test if two GDAL datasets are in the same projection? However, the above does not cover cases where an SRID is not available. It can often be the case that an SRID is ...
0
votes
2answers
58 views

Define a projection for one point

I'm new to ArcGIS and am using ArcMap 10.1. I wanted to find the distance from a point (lat 36N long 12E) to all the polygons in my shape file. People on this forum helped me out and said that I ...
0
votes
0answers
88 views

Kartograph - “projection not named”

The Kartograph package looks very promising, so I have been trying play around with it. As it turns out, I have been able to get the most basic map to work (the "world.json" example), but I could not ...
2
votes
1answer
96 views

How do I set the projection and coordinate system for a TIFF file?

I have a topographic map of California (obtained from CAL-Atlas) as a TIFF file. I tried importing it into QGis, but it displays the map using a pixel based coordinate system rather than ...
3
votes
1answer
113 views

Which projection is being used in this figure?

I would like to use the projection being used in this figure. Does anyone know which one it is? Esp helpful if it is available in ArcGIS. From plant stress page thanks!
1
vote
1answer
80 views

Lambert Conformal Conic Projection Inverse Transform after Fitting Ellipse to Noisy LLA Data

I'm using Python and Basemaps to convert some Lat Lon data to the LCC projection and back again. Since it is noisy data representing the footprint of a satellite, I am filtering it and fitting an ...
1
vote
1answer
52 views

QGis points distance from shore in metres

I have a grid of depth points in the Irish Sea that i'm trying to add other data fields to, in this case distance from shore. I've tried both of these suggestions to no avail, but am having some ...
1
vote
1answer
139 views

In Ogr2OGR: what is SRS?

I am trying to understand this command: ogr2ogr -f "MapInfo File" original.tab wgs84.shp -s_srs EPSG:27700 -t_srs EPSG:4326 I don't understand the s_srs and t_srs paramaters. The help file says ...
4
votes
2answers
802 views

How to convert a NetCDF file to GeoTIFF using GDAL

I have a NetCDF file which contains data for the number of rain days in the UK. I'd like to convert it to a GeoTIFF, but can't get GDAL correctly georeference it. See dumps from gdalinfo below. I ...
2
votes
1answer
46 views

does Pseudo Mercator Projection causes problem while clipping rasters

I tryed to clip a Raster file using an ESRI shapefile using gdalwarp command, but i always get an empty output file or a wrong clip with wrong location. this the command bellow: gdalwarp -dstnodata ...
1
vote
0answers
41 views

How can I obtain the unit of a projection SRID?

Given a projection SRID, is there a way I can obtain the coordinates unit string (meter, degree, ...) ? In PostGIS for example, it looks like it is present in the srtext column of spatial_ref_sys. ...
2
votes
1answer
95 views

Shapefiles from Nationalgrid without a .prj file - what projection are they in?

Im working with these shapefiles: http://www2.nationalgrid.com/uk/services/land-and-development/planning-authority/shape-files/ They show pipelines & electricity grid of the UK. They do not ...
0
votes
0answers
56 views

QGIS: Albers projection in lat lng?

I'm trying to make a map of Russia in the Albers projection. My projection string is: +proj=aea +lat_1=45 +lat_2=70 +lat_0=40 +lon_0=100 +x_0=20 +y_0=20 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m ...
7
votes
1answer
226 views

Can I just swap out a .prj file to reproject a shape file?

I'm an experienced software developer -- but a GIS noob. I have a shape file that I am trying to turn into a SVG map with Kartograph. When I try to run Kartograph I get this error: ERROR 6: No ...
0
votes
1answer
153 views

Projection problem with ESRI JSAPI and ArcGIS map service

I was trying to obtain a gpx file with some coordinates by drawing on an Openlayers map with an ArcGIS baseMap. When I draw the polyline and create the gpx, if I open it on Google Earth, what I see ...
2
votes
0answers
14 views

Eliminating/minimizing distortion in 200 NM EEZ buffers [duplicate]

I frequently need to calculate buffers of 200 nautical miles from country or baseline polygons in order to map maritime Exclusive Economic Zones (EEZs). However, I've noticed that when generating the ...
1
vote
1answer
167 views

Add EPSG:3857 geometries to map using Leaflet

Right now Leaflet can only add geometries with latitude and longitude values onto the map. If we have a EPSG:3857 point, whose x=-11819829 and y=4200860, how can I add it onto the map? If this point ...
0
votes
0answers
15 views

How to Create Consistent Grids using different Projections [duplicate]

I would like to be able to create highly accurate and consistent grids to be used in my simulations. I will need to create 200m2 grids for the UK. The processing software will need data in Lambert ...
2
votes
2answers
102 views

Problems with transformations in ArcMap

I have files projected in British National Grid. After I have transformed them into WGS_1984. I noticed that if I were to transform them back to BNG the original would not match the new. Is there a ...
2
votes
2answers
70 views

Measure areas, lenghts in specific regions (Australia, Sout East Asia)

I'm in need to find a suitable projections to measure correctly areas and lenghts for 2 areas of interest. I want to measure both factors for: 1) First region Australia & New Zealand (1st ...
2
votes
1answer
93 views

How can I transform Real-time Local position system coordinates into GPS/WGS84?

I have a local coordinate system built with Ubisense sensors and tags (it is a real-time locating system used to automatically identify and track the location of objects or people). The local ...
0
votes
0answers
26 views

alignment of shapefiles in GRASS

I have two shapefiles below. One is in the state plane projection, and the other is not projected. In ArcMap the shapefiles line up perfectly. When I import them to my mapset (using the override ...
8
votes
1answer
172 views

Mercator bias plot in Leaflet

I was inspired by this wikipedia image from the mercator projections page to hack around with leaflet. The idea was to interactively have your cursor move a continent and that it would be corrected ...
6
votes
3answers
249 views

How can I obtain the same area values provided by the Census for TIGER boundaries using PostGIS functions?

In PostGIS, how can I compute the area of Census Boundaries and obtain the same results as are provided by the Census? For example, most Census Boundaries include attributes for Land Area and Water ...
4
votes
1answer
205 views

Why is tiff different in epsg 3857 and epsg 900913 in gdal

When I transform tiff from 4326 to 3857 and from 4326 to 900913 in gdal, I get different result(when display in Qgis) eventhough these two projections(3857 and 900913) should be the same. What is ...
0
votes
1answer
125 views

Field Calculator returning incorrect length and area values when QGIS project is reopened

Similar to Field Calculator returning incorrect length and area values, but as always slightly different. I have QGIS 2.0 and when I create a polyline shapefile, the field calculator returns the ...
1
vote
1answer
34 views

Is it due to irregularity of geoid, we cannot convert the height between spherical datum and local datum by cs2cs?

Is it due to irregularity of geoid, we cannot convert the height between spherical datum and local datum (which uses locally defined geoid and height) by cs2cs? What I mean is that, by using cs2cs, ...
3
votes
1answer
70 views

How to select projection

I have to compare geometries anywhere in the world; mainly between 65N and 40S but also in the Arctic latitudes. I need "commercial accuracy" - not military or navigational. For example does a line ...
2
votes
1answer
82 views

Identifying coordinate system for Jersey

I'm trying to plot some X,Y coordinates which should be located on Jersey (the British dependency, not the state). The metadata that came with the points is as follows: Coordinate System: ...
8
votes
1answer
194 views

Using customized Coordinate System for Archaeological site data

I don't know so much about coordinate systems... In my office we use to deal with spatial data coming from archaeological sites. Each site has its own x-y-z coordinate system (GCS). Three simple ...
3
votes
1answer
108 views

Convert planar distance to ellipsoid (real) distance

I have the following linestring which approximately marks an airport runway: LINESTRING(-381578.819887 6574044.360475, -378513.534443 6574799.475787) # EPSG 3857 LINESTRING(-3.427781 50.732117, ...
1
vote
1answer
148 views

Change coordinate system using SQL or Javascript

Is there any built in function in SQL Server 2008 R2 which can transform the cordinates from 102100 to 4269 coordinate system something equivalent to ST_Transform from postgres. If there is algorithm ...
2
votes
2answers
98 views

How do I set a CRS when it isn't listed in QGIS? (Mac, not PC)

I want to work with a shapefile that is in a Coordinate System that I can't locate in QGIS for Mac. When I load this shapefile data, it shows up fine, on-the-fly has generated the CRS data most likely ...
2
votes
1answer
142 views

using PostGIS to calculate distance of a route over a large area

I'm new to PostGIS and looking to measure the distance of the Pacific Crest Trail which spans western North America from Canada to Mexico. I have a data set containing the lat lon and dates from GPX ...
2
votes
1answer
74 views

How can I get the ellipsoidal values for length and area using spatialite?

I have spatialite geometry data stored in a spatialite database in WGS 84 (EPSG 4328) format: SELECT Srid(geometry) FROM shape_layer; > 4326 When geometry is being returned as text, it is ...
4
votes
2answers
85 views

Why is it not advisable to perform spatial analysis on layers with source datasets having same datum but different projections?

I have read that it is not advisable to perform spatial analysis on two layers with source datasets having the same datum but different projections loaded in ArcMap. Since the second layer should ...
1
vote
1answer
101 views

Aligning layers with questionable metadata in SW Ontario

After making my best efforts to read/try everything I can on this forum and elsewhere, I unfortunately have to contribute to the wide literature of "my layers aren't aligning" questions. I am working ...
1
vote
1answer
348 views

Pseudo-Mercator projection with Decimal Degrees?

Hope this isn't a duplicate, did some searching but none seemed quite the same. Projection I want: WGS84/Pseudo-mercator. Selected. Looks Great. Canvas units I want: Decimal Degress. Selected. ...
1
vote
1answer
84 views

How to reproject from Clarke_1880_RGS_Lambert_Conformal_Conic to ETRS_1989_LAEA?

I am unable to reproject Marseille shapefiles from Clarke 1880 RGS_Lambert_Conformal_Conic to ETRS_1989_LAEA. I know that Clarke is a geographic coordinate system and it has no datum. I have tried ...
0
votes
1answer
53 views

how to correct merge rasters with different projections? [closed]

how to merge rasters with different projections with correct transforn? For example EPSG:32636 and EPSG:32637 if i do it with gdal_retile command, i have correct view for EPSG:32637 rasters and ...