Tag Info

New answers tagged

1

In your case you can add the item to define the crs string to the URI like &crs=EPSG:4326. Your code should look as follows: uri = "file:///C:/data.csv?type=csv&xField=lng&yField=lat&spatialIndex=no&subsetIndex=no&watchFile=no&crs=EPSG:4326" vlayer = QgsVectorLayer(uri, 'Points', "delimitedtext") ...


2

Can you try this (change GeoJSON to the format you want to load.): vector_format = new OpenLayers.Format.GeoJSON({ 'internalProjection': new OpenLayers.Projection("EPSG:31466"), 'externalProjection': new OpenLayers.Projection("EPSG:3857") }); result = vector_format.read(newFeatures); vectorLayer.addFeatures(result); This worked for me.


3

You can't transform from one SRID to another without knowing what the SRID you are transforming from is. It looks like in your case that the coordinates are Spherical Mercator, which is SRID 3857. So, if this is true, then you can use ST_Transform in conjunction with ST_SetSRID: UPDATE roads SET geom = ST_Transform(ST_SetSRID(geom, 3857), 4326); and then ...


0

Thats because effectively you say "the coordinate 698745.50201423 4210011.04002000 is in SRID 4326", which is not what you want. You want to transform the coordinate from your source reference system to a destination reference system. So you need to: Know the source coordinate system Use ST_Transform ( see http://postgis.org/docs/ST_Transform.html )


3

I bet those values are US survey feet, and based on the document, also on NAD 1927, not NAD 1983. The app you're using is using the NAD 1983 definitions of the State Plane zones. The parameters are different, so you're not going to be able to convert NAD 1927 coordinates using it. If I convert the given values (cropping to integers) using the NAD 1927 ...


1

You first need to import the CSV and give it which fields are x and y co-ordinates and the projection of your data. This should be the large comma icon which says Add Delimited Text Layer. If you then go to the Vector menu (you may need the Ftools plugin installed but this comes as standard in recent versions of QGIS I believe) then Analysis, you have a ...


3

This issue has been sleeping here for long, but this might help some googler: For a similar task I simplified the functions from the website that you mention to the following, it works fine for me (in Python): def LatLonToPixels(lat, lon, zoom): tileSize = 256 sinLat = math.sin(float(lat) * (math.pi/180)) py = (0.5 - math.log((1 + sinLat) / (1 - sinLat)) / ...


2

This is pieced together from the link @PolyGeo commented. Copy/paste this into the Python window: sr = arcpy.SpatialReference() sr.loadFromString('{B286C06B-0879-11D2-AACA-00C04FA33C20}') mxd = arcpy.mapping.MapDocument("CURRENT") df = arcpy.mapping.ListDataFrames(mxd)[0] df.spatialReference = sr arcpy.RefreshActiveView() I tested it in ArcMap and it ...


2

The source code of the application page shows that WMS layers are read with parameter "&SRS=EPSG:22185 A test with gdaltransform http://www.gdal.org/gdaltransform.html gives support for this: gdaltransform -s_srs epsg:22185 -t_srs epsg:4326 5434921.2799996715 6359301.360077026 -60.6956426930295 -32.9071417880402 0 Not quite same as your numbers but ...


1

It's probably Argentina zone 5 which has a central meridian at 60W and uses transverse Mercator. The latitude of origin is at 90S, thus the large northing values. The false easting at the central meridian is 5500000 meters. Scale factor is 1.0. The EPSG Geodetic Parameter Registry has several zone 5 listed based on different geographic coordinate reference ...


1

I don't know the software you use, but I could get the data into QGIS: The corner points and the one from the second screenshot seem to be correct in North Kansas, and correspond to real estate borders in Google satellite imagery. Two sides are made up of streets that are in OSM maps as well. As you found out, the base point WGS84 coordinates are wrong ...


0

You may have swapped the coordinates somewhere. If I reproject your resulting lonlat coordinates 103.919768 1.125312 103.690059679 1.35650722603 I get with cs2cs using: cs2cs -f "%%.6f" +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs +to +proj=tmerc +lat_0=1.366666666666667 +lon_0=103.8333333333333 +k=1 +x_0=28001.642 +y_0=38744.572 +ellps=WGS84 ...


0

Hm, ok, let's make a proper answer from my comment: Google Fusion allows you to import data from a number of sources, including csv and kml. But as far as I understand, it only understands plain data tables during csv-import. When you exported your geometry as a csv-file, QGIS used the Well-Known Text-Format to represent it in one of your table's fields ...


0

Coord sys tab ArcMap 10.2.2 ArcMap tells me that DHDN Gauss Zone 3 is also Bessel based (the Deutsches Hauptdreiecksnetz datum). So no trandformation is required. If you do want to transform your data to a WGS84 base, then there are a stack of transformations available. Including Ntv2 method.


1

My preferred solution is to build a custom CRS in QGIS, and test if sample coordinate points are placed correctly compared to Openstreetmap or Google imagery from the openlayers plugin. In Russia, Gauss-Krüger transverse mercator based on the Krassnowsky ellipsoid is common use. The projections named Pulkovo are usually 3 or 6 degrees wide, with a false ...


1

I recommend ProjFinder. The principle is "zoom on the place you are looking for and the tool will provide the supposed projections". You can also use epsg.io and search Russia to sort out possible projections


1

Based on Identifying Coordinate System of Shapefile when Unknown? it directed me to a tool which is very helpful to find relevant CRS which is exactly I was hoping for: http://www.epsg-registry.org/ The result in my case:


2

For the Openlayers plugin, the Project CRS must be in EPSG:3857. Your other layers can have different Layer CRS, if you have enabled On-the-fly-reprojection. BTW, current version of QGIS is 2.4, and the openlayers plugin does not support older versions anymore.


1

The problem with your solution is that source_srs is not a valid osr.SpatialReference(). If the result of source_epsg is 4269 then: source_srs = osr.SpatialReference() source_srs.ImportFromEPSG(4269) gives a valid osr.SpatialReference() NEW If I understand correctly your question, you want to use Leaflet, and Leaflet expects coordinates and GeoJSON ...


1

The first step is ensure which data have the proper information, for this matter I would try to get the coordinates from other resources (google maps, OSM, geographic services in your country),if you can identify a geodesic vertex will much better. When you compare with your data you can identify the wrong information. In case of your DGN file have the ...


1

I think what you need is to geo-reference your data. Here's a link: http://docs.qgis.org/2.2/en/docs/user_manual/plugins/plugins_georeferencer.html and I'm sure ARCgis has something similar...as does Python+gdal, and any legitimate GIS program. The basic problem is that your coordinate system is totally non standard so doing a projection change will not ...


1

An oblique mercator projection might solve your issue. See this Q&A for details: Using customized Coordinate System for Archaeological site data


1

You would only use a datum transformation if you wanted to transform your data based on Bessel to another model like WGS84/ETRS89. If all your data has a common (Bessel) base to don't need to do this. When the data frame in ArcMap has data with several different datum(s), a warning should pop up. Get to the dataframe properties page, coordinate system tab. ...


0

As long as you stay on the bessel ellipsoid, your data is pretty accurate after reprojecting to Gauss-Krüger. You might run into datum shifts if you add WGS84 (or ETRS89) based data. There is a bunch of valid datum shifts between bessel and WGS84, depending on the part of Germany you work on. Most accurate will be using a NTV2 datum shift grid, but this is ...


2

You might see both datasets aligned because On-the-fly-reprojection is enabled. This works when both datasets have different CRS. Other software does not offer this tool, so you have to reproject one of your datasets to the CRS of the other to make them align in every software. BTW this applies also to some tools integrated in QGIS, like intersection or ...


2

I find openWind normally works very well so, without any further information, I suspect you are spot on about mismatched CRS. According to the documentation: openWind is fundamentally based on a meter grid so the projection only comes into play when converting to and from geographic coordinates. openWind does not carry out on-the-fly projection so ...


0

As mentioned in the comment, a possible problem is the precision of your dataset, which could eplain that the data do not align. However, 20 m seems to be quite large especially in Kentucky where I would expect bing map to be at least below 5 m. The more likely issue is the absence of transformation between WGS 84 and NAD83 when you use "on the fly" ...


4

Maybe check out the properties of Projected Coordinate Systems, to get a view into their utility? There are 3 aspects or properties presented in Projected Coordinate Systems that establish their utility and rationale. Any projection of 3D space on a 2D surface will of course exhibit distortion versus reality. Depending on your application, using a specific ...


7

There's a good answer over at Stack Overflow, which goes a little something like this: The geography type is a little bit more restrictive than geometry. It can't cross different hemispheres and the outer ring must be drawn counter-clockwise. The rest can be found here. Another article goes into some more detail: If you’re looking for the ...


2

Traditionally, topographic maps are plotted using a conformal projection, not an equal area projection. A conformal (or orthomorphic) projection preserves angles and, at any point, has isotropic scaling. Such qualities allow relatively easy computations involving angles and distances. en.wikipedia.org/wiki/Map_projection#Conformal ...


2

Here is the source to the underlying Java library, prj2epsg, used behind the scenes on the webpage you list. Basically, it uses a Lucene index to get the best match between the WKT in your prj file and an underlying EPSG. As AndreJ has already said, this may not be 100% perfect, but Lucene excels at partial/fuzzy matching. gdalsrsinfo might be easier to get ...


2

There is no such tool working 100% perfectly, because there are many EPSG codes that share the same projection parameters. You can run gdalsrsinfo on any Geotiff or shapefile .prj file to get the proj string out of the definition. For some intelligent ways of guessing, follow the answers given here: Identifying Coordinate System of Shapefile when Unknown? ...


3

Try the EPSG Geodetic Parameter Dataset which is more up-to-date and where epsg.io got its information. Admittedly, it doesn't always have projected coordinate reference systems that are suitable for an entire country--but only because no one's told us what is used for a map of the entire country! Spatial Reference allows user-contributions so might have ...


3

Try epsg.io. You can type in the name of a country or even search by CRS. And it is free!


0

If you want to extract value from a SRTM data then you should use a point shapefile because raster image change their pixel value at different level and in polygon layer you can not find right value. so you have to need a point shapfile to extract value.


2

The above code looks more like you just clone shp into shputm and then assign the output of crs(shp) to shputm without performing an actual reprojection. Anyway, if you import both the shapefile and the NDVI raster, and then reproject shp using spTransform, subsequent data extraction should work out fine. Also, the output of extent(shp_utm) roughly agrees ...


2

As you've mentioned, the image contains very little georeferencing information. And, as you're only looking for a 'close approximation', you could bring the image into QGIS and use the georeferencer. It's an easy to use tool, and hey - you might even get the image georeferenced closer than you think! Here's a great tutorial: ...


1

ETRS89 and WGS84 are not the same, although the differences are minor. Some time-dependent transformations between ITRFyy and ETRF2000 are listed here with the XYZ offsets at the centimeter level. ETRS/ETRF is plate-bound (to minimize changes in coordinates over time) while WGS84 is tied to ITRF. This occurs in North America too where NAD83 is tied to the ...


2

Could your question be reformulated to: Features of which (real world) size are correctly represented in this data set if its resolution is 1:10m? I had that question to the Natural Earth data set. After talking to colleagues and finally reading this post Appropriate pixel size when converting vector to raster I made up my answer. I am not sure, if it is ...


3

As you discovered, if the difference in Semi-minor axis is not important for your needs you can consider that they are identical systems. And if you use any program that is using Proj4 projection library (GDAL, QGIS etc.) there will be no difference between these two. You can test it yourself with gdaltransform http://www.gdal.org/gdaltransform.html ...


3

The EPSG registry describes the two CRS as very similar and in some areas interchangeable. In "Area of use" section: EPSG: 32632. Between 6 ° E and 12 ° E, northern hemisphere between equator and 84 ° N, onshore and offshore. Algeria. Austria. Cameroon. Denmark. Equatorial Guinea. France. Gabon. Germany. Italy. Libya. Liechtenstein. Monaco. Netherlands. ...


0

Google Mercator is now EPSG:3857, while 900913 has been dropped from the list of EPSG codes. Furthermore, there is some kind of hack inside the projection definition, because Google mercator is calculated on a sphere (a=b), but the lat/lon coordinates are that of the WGS84 ellisoid. This is only implemented correctly for EPSG:3857.


0

To check the spatial reference, right-click the feature class/shapefile/raster and select properties, then the source tab. You should see both a projected and geographic coordinate system. If you don't, or its wrong, follow Erica's answer.


0

There are two issues that you need to solve. Firstly, the polygon that you have, is in a format that is called the WKT. You will have to convert it to a geometry in the ESRI's JavaScript format. I have used Wicket in the past to do this conversation for me. Once you have an ESRI Polygon, you can use the project operator on the GeometryService. You should ...


2

First open up ArcToolbox. Then there are two possible tools you can use (both in the Data Management / Projections and Transformations toolbox), depending on the specific situation: To define the projection, use the Define Projection tool. Do this when: no projection is currently assigned, or the current projection is incorrect (e.g., data should be in ...


0

Open the original file in a blank project (set the correct EPSG of the project first) Disable "on the fly" transformation. Save the shp adopting the new epsg. Now, if your raster is in 3857, your shape file must be ok without "on the fly" transformation.



Top 50 recent answers are included