Tag Info

New answers tagged

0

Esri software does not have a built-in transformation to convert between NAD 1983 and NAD 1983 CSRS in Ontario. The Ontario Ministry of Natural Resources and Forestry provides an NTv2 file to convert between NAD 1983 (original) and NAD 1983 CSRS. You can download it from COSINE. You have to apply, but it's not onerous, and the NTv2 files are free to ...


1

You can shift the data into the correct position using these GDAL commands: gdal_translate -a_srs EPSG:4326 -a_ullr 0 0 360 -90 NETCDF:"sic_average_nclimate.nc":SIC_Change change360.tif gdalwarp -t_srs WGS84 change360.tif change180.tif -wo SOURCE_EXTRA=1000 --config CENTER_LONG 0 (with a little help by Frank Warmerdam: How to reproject raster from 0 360 ...


0

The lower left corner is at (0,0) coordinates, but for me (0,0) is the coordinate of the upper right corner in your case and I don't know any geographic coordinate system with its origin at -90. As you work in ArcGIS, you could use the georeferencing toolbar to move your data at the right location. Move the upper right to (0,0) and the lower left to (-360, ...


1

(This isn't an answer, but rather a process suggestion that is too long to be a comment) You could geo-reference it in QGIS using the GeoReferencer tool as you appear to be able to identify common points on both rasters. This would generate a GDAL script with a set of GCP points, and transformation parameters. You could add this script with a sample of ...


1

Redefining the original file as WGS84 does the trick at least for accuracy for any practical purpose. The following was sent by a customer care rep at ESRI... 1] ITRF 2008 is a datum definition that takes continental drift into consideration. 2] The WGS 1984 definition used in ArcGIS Desktop is the original definition, and has not been updated to take ...


3

To find out the right CRS, create a new project in QGIS with project CRS set to EPSG:3857, load Google or OpenStreetMap background from the Openlayers plugin, and look where your data is placed. If you set the Layer CRS of your data to EPSG:32749 WGS 84 / UTM zone 49S, your data will be placed in the right position (at least the same place a Google search ...


2

Those input points are not in urn:ogc:def:crs:OGC:1.3:CRS84, since that is (roughly) WGS84 lon / lat, and (taking the first point): [ 383707.21875, 9211513.0 ] is not a reasonable lon / lat combination. What QGIS is (probably) doing in converting that point to -52.78125,9211513.0 is taking 383707 and wrapping it around a few times (383707.2185 - 1066 * 360 ...


1

Not really a answer but a valid workaround: because the CreateLayer() method accept a SRS as parameter, one can create a new empty layer with the correct SRS and then fill it with the features from the input layer: import ogr driver = ogr.Open(input_file).GetDriver() datasource = driver.Open(input_file, 0) input_layer = datasource.GetLayer() dest_srs = ...


4

The northern two-thirds of Georgia should be pretty good, because the South Carolina coordinate reference system is Lambert conformal conic-based. Thus, the standard parallels extend through Georgia too. I ran a point at 31N 85W through the National Geodetic Survey's SPC program to see what the distortion would be. Note: South Carolina's zone is 3900. It ...


1

It is called the Equirectangular projection, plate caree or Geographic projection. This last name is nearly worthless in the age of Google. It is an ancient method associated with Ptolemy and very commonly used by nasa and other scientific endeavors where its size and shape distortions don't matter as much as ease. Just Google plate caree and click on ...


1

Displaying geographic coordinates (i.e.lat/long) as if they were 2D cartesian coordinates is similar to using the "Plate carrée" coordinate system (also called equirectangular). However, you will have a scale factor difference so it is not straightforward to put your points on top of the map. Therefore the suggestion to use a specific software is a good ...


1

When you change the projection via the properties dialog, I don't believe you are re-projecting the data, you are asserting that the data is actually in the projection you are setting it to. That's why it's all screwed up when you try to use it. You need to use the "Project" tool in the Arc Toolbox. It's all explained here. Even though the article refers to ...


0

If you have two suspected spatial references for the list of coordinates, here are some steps to confirm if they are correct or not. Open up new ArcMap Add one of the ESRI general basemap WMS layers (one that has data for entire Earth) For dataframe select Properties>Coordinate System tab, change the spatial reference to one of the suspected spatial ...


1

Google maps uses WGS 84 Web Mercator. If you've tried creating your points with this coordinate system and haven't been successful, there is probably something wrong with your inputs. The commas for decimal points raises an eyebrow for me. Replace the commas with periods and see if it works.


1

Tend to agree with @chris-w, if you look at the National Map, NED data) are not projected - though projections vary across the Survey, many times based on regional project needs (and if it's part of Mapping, Biology, Water, etc.). The USGS is spread across the landscape, typically with at least one office in each State, all with national, regional or local ...


3

The short answer is no, the projection used by the USGS varies with product (map series), application (paper vs web vs GIS data), and department/region/whatever. If you really want some detail, they publish a document on projections called Map Projections: A Working Manual you can find at http://pubs.er.usgs.gov/publication/pp1395


0

I'm not a mathematician so may be my idea is flawed? There are more clever people haunting this forum than I. A possible way of doing this is set your centerx and centery to zero and compute the range of values then add those to your real world XY position. An example of this is shown in the screen shot below. So i is your count (I did 1 to 100), angle is ...


1

Different infos: some lines are not useful By default, these below projections already exist so you do not need to declare them Proj4js.defs["EPSG:4326"] = "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs"; Proj4js.defs["EPSG:900913"]= "+title=GoogleMercator +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m ...


0

Ok, I think I figured it out. Apparently the map canvas has its own CRS and on the fly projection for layers which use a different CRS is disabled by default. Enabling OTF projection with my_canvas.setCrsTransformEnabled(True) did the trick. (my_canvas being the QgsMapCanvas in my Qt window). my_canvas and my_layer actually both had the EPSG:4326 CRS ...


2

In QGIS, goto Settings -> Custom CRS, and Copy from existing CRS. take a lcc projection based on WGS84, like EPSG:3762 +proj=lcc +lat_1=-54 +lat_2=-54.75 +lat_0=-55 +lon_0=-37 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs and replace the values to your system: +proj=lcc +lat_1=17.5 +lat_2=19.5 +lat_0=12 +lon_0=-102 +x_0=2500000 +y_0=0 +ellps=GRS80 ...


2

I would prefer EPSG:3035. The ESRI codes might not be available on all platforms: EPSG:2163 has a different lon_0 leading to a distortion of the map:


1

Actually it would work as both are about ~~~~ the same latitiude but use the Euro version http://spatialreference.org/ref/esri/102013/


4

You could calculate ST_Area on a geography type. Since you have data with WGS84 (SRID=4326), you can add a simple geography cast, e.g. SELECT ST_Area(geom::geography) which will return area in m² on a curved surface (sphereoid by default). This should be pretty close to the true surface area, without requiring any projection. It would be interesting to ...


0

I'll take Melita Kennedy's link above as the best answer to what the string representation's elements are. And note that she's asked for this information to be added to the ArcGIS Help in the future. Thanks MK! Also thanks to Vince for additional info. minimum x value minimum y value xy precision (1/precision = xy resolution) minimum z value z precision ...


0

My approach using regular expressions directly on the WKT string function validateWKT(wkt){ var match = wkt.match(/\d+\.\d+/g); for(var i=0; i < match.length; i=i+2){ if((match[i] > 180) || (match[i+1] > 90)) { return false; } } return true; }


1

KML coordinates are in EPSG:4326 by definition. WKT lacks any concept of CRS whatsoever, encoding just the geometry type and its coordinates. So there is nothing within the format's themselves that would allow you to force coordinates into EPSG:4326. However, as virtually all other terrestrial coordinate systems will use meters (or incredible, as it may ...


1

You haven't defined your spatial reference. Your tool has passed a spatial reference object to your script as a parameter, but you script does not do anything with it. Simply passing it to your script does not define the spatial reference. 2 options: Don't pass a spatial reference. Instead set the Output Coordinate System in the Environments... -> Output ...


3

PRJ files define the projection of the shapefile. To create one define the projection in ArcCatalog either by using the tool Define Projection or right click on the layer and select properties (there's a whole dialog there). It would also be sufficient to copy the prj file from your input and rename it to match the shape file. Considering you're doing this ...


1

Okay, based on the comments, I'll provide an answer: No, there are no EPSG codes that specify geographic coordinates in (lon,lat) order. The OGC, however, did define a code for geographic coordinates in (lon,lat) order, specified in OGC document http://portal.opengeospatial.org/files/?artifact_id=30575 The full URN for the (lon,lat) ordering of WGS84 ...


2

PostGIS typically expects coordinates in longitude-latitude or E-N order. Looking at the second example from postgis.org/docs/ST_AsGML.html, it seems there is some flipping of coordinates: -- Flip coordinates and output extended EPSG (16 | 1)-- SELECT ST_AsGML(3, ST_GeomFromText('POINT(5.23423 6.34535)',4326), 5, 17); st_asgml -------- <gml:Point ...


1

Finding the center is not as simple as you think. take an example square in EPSG:4326: Transform it into World Mercator, and the center is somewhere else: In Lambert conformal conical, it is not yet a rectangle: And same for azimutal equidistant: So be careful if you think of a "simple" rectangle and its center point. The world is not a plane! My ...


2

Vincenty's formula (ellipsoid based) is more accurate than haversine (sphere based). Also, lat and long are usually expressed in degree, but your coordinates are not in 0-180, therefore you could be in another system than expected.


1

Thanks Joseph and AndreJ for responding. Just in case anyone reads this and is interested, I found another work around. I loaded the delimited layer (which had the lat longs), saved it with a CRS of British National Grid. Then reopened this layer and created a query where I created 2 new fields, one with the x coordinate and the other the y coordinate (in ...


2

In Settings -> Options, CRStab, select Prompt for CRS for new layers. Then you can choose WGS84 when loading the delimited text file. The other file should remain in BNG. Don't use Set CRS for Layer to change it. This will NOT reproject your coordinates. Instead, use Save As... on the delimited text layer, choose a different filename and BNG as CRS. ...


1

It sounds like it would be more practical to make a polygon if you need a very wide, geographically consistent "ribbon." I suggest that you buffer your original line and style that instead. If you play around with styles you should be able to hide the fact that it's a polygon rather than a line.


1

Edit: Seems I misunderstood the question. Leaving this answer if someone finds it useful for something else. Under Style, the setting "Map units" is usually in meters (or degrees if you're in an unprojected coordinate system like WGS84,) and you use that when you want the line to be exactly the same size in relation to the geography regardless of zoom level ...


2

I just entered the coordinates into Google maps. If you change them to 35.205357, -111.59330 it puts you in the Flagstaff area. So The coordinates may have just had their decimal places in the wrong places or missing.


1

The latitude value could be 35 20 53.57 while the longitude value could be -111 59 33. Or they could both be decimal degrees, with the appropriate insertion or change of position.


2

The +datum=nad27 parameter overrides the +towgs84 parameter. GDAL can only do grid shift, or Helmert/Molodensky transformation, but not both. Since the grid is more correct in most cases, the developers decided to skip the 3-/7-parameter transformation if both options are given. The transformation for NAD is stored in several grid files, which can be found ...


0

I tried the option 'coordinate system', 'coordinate system folder', 'spatial reference' separately. Nothing works actually. 'Execute Error' is always shown in dialogue box.


2

NAD27 EPSG:4267 and WGS84 EPSG:4326 are both CRS with lat/lon degrees. The extent of your layer is in a projected CRS, but the projection information does not reflect that. The most common pitfall in QGIS is to use Set CRS for Layer, which changes the CRS, but not the coordinates. You have to switch that back, or delete the layer and reload the original, ...


2

I think there may be a bug in QGIS save as. This is from QGIS 2.6.0 (Brighton): The easiest way to export a shapefile to a new coordinate system in QGIS is to right click on the shapefile and select 'save as' then in the dialog select Selected CRS which pops up a dialog and then select the 'to' CRS (in your case WGS84): Using the method employed in ...


1

You should include the program you are using... But if your using QGIS I would avoid using the "Save as" option and instead open QGIS "Toolbox" find the QGIS Algorithm for Vector - "Reproject Layer" made sure to set the source CRS to nad27 and the target to wgs84


1

From wiki/Tessellation A tessellation of a flat surface is the tiling of a plane using one or more geometric shapes, called tiles, with no overlaps and no gaps. I think the same word can be used to describe the tiling of a sphere. If you're after the (very conventional) spherical equivalent of a planar grid, then the word is graticule – the ...


0

The error message you are encountering is telling you that the coordinate systems do not match. For example may be you are trying to copy data that is WGS84 into a UTM defined FeatureDataset? All data copied into the FeatureDataset must match the FeatureDataset..


3

In Settings -> Options -> CRS tab, you can select to Prompt for CRS for new layers. That should avoid the automatic assigning of wrong projections.


0

Maybe Spacedman have already gave the answer but I was actually looking for formulae . I have found this page which is Turkish so I'll give you only the part you can understand. It says with this formulization we can transform our Geographic(Ellipsoidal) coordinates to Cartesian Coordinates. ( "h" is ellipsoidal height) Then I have found this page which is ...


4

I'll use spherical coordinates as defined here on Wikipedia which uses phi and theta (which is probably your lambda). Phi is the angle from the north pole. Hence if the WGS84 point is 10.0.0N, phi will be 80 degrees. For a point in the southern hemisphere, say 12.30.00S, phi will be 90 + 12.5 = 102.5 degrees. Theta is just the longitude in degrees, if the ...


1

This is a common problem, here is another previous discussion: Why some coordinate systems define x-axis as northings and some as easting? There is a very exhaustive discussion at http://wiki.osgeo.org/wiki/Axis_Order_Confusion @wwnick provided the above information as a comment to a duplicate question


3

I am unclear why you prefer the name to the factory code. You can use the srid and there is no fuss with spaces/underscores. For projected systems: http://resources.arcgis.com/en/help/main/10.2/018z/pdf/projected_coordinate_systems.pdf For geog. Systems: http://resources.arcgis.com/en/help/main/10.2/018z/pdf/geographic_coordinate_systems.pdf If you are ...



Top 50 recent answers are included