Tag Info

Hot answers tagged

4

Thanks to Chris W., we were able to find a solution to the problem. In ArcGIS Pro, the coordinate system in ArcGIS Pro for scenes does not initially conform to the layer coordinate system as it does in ArcGIS for Desktop. In ArcGIS Pro you have to specify a coordinate system manually. When a new map or scene is created, the default coordinate system is WGS ...


4

There are two things that must be done. Using your data I set the spatial reference of the shape file to WGS_1984_UTM_Zone_43N (it was undefined) and then repaired the geometry with Repair Geometry. After that the image extracted properly with Extract by Mask: This could be scripted if you have python ability but can also be done on batch.


3

If you load an unreferenced raster into the georeferencer, the question for the CRS is surely useless. The referencing assings values of pixel/line to target coordinates, so the source CRS does not play any role. The target CRS however is important, it depends on the way you are doing the georeferencing. You have lat/lon grid lines imprinted on the map, ...


3

I am no expert in this but from my understanding: The OpenLayers plugin in QGIS uses the EPSG:3857 CRS which is a projected CRS on a flat surface (here's a very good post describing it). Therefore, it calculates a straight-line distance as you would on a paper map. I can't find how Google Maps calculates its distances but a common method would be to use ...


3

Almost all software for doing coordinate projection use geographic coordinates as a standard system in the middle and defines "forward" (from geographic to projected) and "inverse" (from projected to geographic) routines for projections. So, to go from a UTM projection (say "UTM 10 N") to a stateplane projection (say "Washington Stateplane North") you'd ...


2

A good way to figure this sort of thing out is to manipulate the two layers interactively. Translate and rotate one to make it coincide as well as possible with the other. If you can succeed in this, then (a) the problem may simply be that an incorrect datum (or coordinate system) has been assigned to one (or both) layers and (b) regardless, you will have ...


2

You'll have to download the EPSG database and pull the information you want from it. They do provide PostgreSQL-compatible downloads. http://www.epsg.org/DownloadDataset


2

I'd use something like EPSG:3035 - it's a reasonable European projection that is equal area so it's suitable for most statistical mapping.


2

You can create a custom CRS with these parameters: +proj=omerc +lat_0= -22.5 +lonc=25.09 +alpha=0.910238 +k=0.99977264 +x_0=0 +y_0=0 +gamma=0 +a=6378249.145 +b=6356514.966398753 +towgs84=-143,-90,-294,0,0,0,0 +no_defs +to_meter=10000 And you get the 10km-grid as described: I took the old ARC 1950 datum from EPSG:4209 as base, which was common in ...


2

KML files use WGS84 LL by default, so yours should appear correctly positioned with respect to another dataset that you are confident is georeferenced (such a reference dataset is very useful when importing new data) However if the DXF file has not been supplied with any description of the coordinate system used then you have a few options. Ideally you ...


2

Yes, the location central meridian will change the pattern of distortions in most map projections. In the polyconic projection the length of the central meridian is correct, and also along latitude lines (which are not straight). The latitude of origin doesn't affect the pattern of distortions, but only sets the Y (Northing) = 0 location. For China, if your ...


2

A very simple brute force approach: take the first points coordinates and convert them from ISN93 / Lambert 1993 to WGS84 degrees using cs2cs in the OSGEO4W shell cs2cs +init=epsg:3057 +to +init=epsg:4326 -f "%%.8f" <ISN93.txt >WGS84.txt build a local omerc CRS on that point, with the "local coordinates" as false Easting and Northing convert the ...


1

"Erroneous" is relative to your accuracy needs. Let us therefore estimate the accuracy in terms of the distance the boat has traveled: by means of such a result, you can decide when positional calculations become "erroneous." I understand the question as saying that mapping is carried out in an azimuthal equidistant coordinate system centered at the boat's ...


1

Thank you @mkennedy for your input. I am posting an answer to my own question in case anybody stumbles across this issue. From this website here, I was able to download the same dataset, but as .tif with pre-defined CRS. Go to the EarthExplorer from this aforementioned website, choose "Land Cover / GLCC" and take the .tif file. Registration (free) is ...


1

No, In fact arc map uses map units or page units for label offsets so this distance is not related to projection anyway. As ESRI says "These units are measured in map units or in page units (millimeters, inches, or points)." So there is no matter if the layer is in GCS or PCS. Details are at here and here.


1

You can use Field Calculator to get highly accurate geodesic lengths of features in a feature class, regardless of the coordinate system. This means that Arc will find the shortest route across the surface of the ellipsoid when connecting vertices of your lines. Here's how to do it: Open the attribute table of your line feature class. Add a new ...


1

The best way to find out which layer is correct, is to set the project CRS to EPSG:3857 with on-the-fly-reprojection enabled, then load a Google or Openstreetmap background via the OpenLayers plugin, then add your layers and check their layer CRS. Then you see which layer ist placed on the right spot, and which might have a wrong CRS. BTW this page ...


1

Use the function nowrapSpatialPolygons at the anti-meridian of your central longitude. This doesn't work with wrld_simpl from maptools, but it does work with countriesLow from rworldmap. library(rworldmap) data(countriesLow) library(maptools) prj <- "+proj=robin +lon_0=-198 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs" x0 <- ...


1

Have you checked out the tool Regular Points? I believe this is what you are looking for. It can be found under Vector - Research Tools - Regular Points...


1

Error 000289 is probably an ArcGIS error message. The complete description says: The spatial reference of the dataset cannot be altered. The dataset may be in use by another application and therefore locked. The error message makes it sound like you tried to use Define Projection or the data's property page to change the coordinate system. That ...


1

Thanks AndreJ, I did some further research and ended up with a custom CRS file as you suggest and that solved the problem. Contents of the CRS for this case: +proj=utm +lat_0=32 +lat_2=40 +lon_0=-78 +lon_1=-75 +lon_2=-72 +datum=WGS84 +units=m +no_defs


1

First part is getting the point cloud on the correct scale, this can be done with GCP that are set to known real-world co-ordinates, or tied to GPS. Measurement functionality isn't present within VisualSFM, so Meshlab will need to do the job for you. Once you have imported the PLY file that visualsfm has generated into Meshlab, click edit, Measuring tool. ...


1

As you say you are using an image with GPS data in it the information is going to have been most likely stored in WGS84. Identify the part of the world you are working in, either by researching the source of the image and or imformation on the image. From there either project the GPS data using WGS84 as the datum into an appropriate UTM Zone that covers ...



Only top voted, non community-wiki answers of a minimum length are eligible