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  • 37 votes cast
Jul
20
comment Running LAStools on QGIS 2.8
Check this rapidlasso.com/2013/09/29/…
Jun
22
comment extract x-y from a point created from lat/lon coordinate
I think, if your data is on lat lon, EPSG 4326 (lat lon wgs84) for instance, you must reproject it to 32634 (UTM 34N WGS84). You can do this by selecting the layer and choosing save as and defining the new crs. The resulting file will be a shape file where you can use the field calculator to extract the $X and $Y coordinates. Now you can export the table as a CSV file that you can open with a spreadsheet, Excel for instance Hope it helps Gerardo
Apr
20
comment How to properly get the slope from an ASTER DEM in QGIS?
Aster DEMs are in lat lon WGS84 (EPSG4326). In order to calculate the slope correctly you must define the "ratio of vertical units to horizantal units" as 111120. For more information look at this answer gis.stackexchange.com/questions/95337/…. Although it is meant for hill shading, the parameters mentioned also afect slope calculations. In order to work with a CRS in meter you must reproject the original file using raster/projections/warp (reproject) not what you describe in your comment
Apr
5
comment Which UTM zone to use for a large country?
Being near the equator also matters since it does have a double false value to asign the north value. For features north of the equator its false value is 0 meters. For features south the equator its false value is 10,000,000 meters. In your case, you have both cases, areas to the north and south of the equator making the use of a UTM CRS a little bit problematic
Mar
19
comment QGIS georeferencer: Thin Plate Spline (TPS) residual
In my experinece yes, I expermented with lineal, helmert polynomial and Thin plate spline with the same image and control points. For reference I created a UTM vector grid using mmqgis. Then I compared visually the vector grid and the utm grid in the georeferenced images and Thin plate spline aligned perfectly. What I did also was to define the control points in utm to define a square area (4km x 4km)
Mar
14
comment Microsoft Visual C ++ Crash when Install qgis.2.8.1
I have the same issue on a machine. My OS is win 7 64 and I have tried with the stand allone or OSGeo4w 64 bits installers. I know about this thread gis.stackexchange.com/questions/72506/… and this one also stackoverflow.com/questions/14552348/… but I have not been able to solve the issue
Mar
8
comment How to automatically convert dots on paper maps to vector points?
I think that you have to create a new vector layer (shape for instance) and capture your points manually...
Feb
11
comment Buffering in km in NAD83 QGIS
you have to reproject to a CRS that handles meters as a measuring units for the coordinates, and that preserve the NAD83 datum
Feb
3
comment Calculate shortest path not on land but over sea
The main problem is that the navigation routes I have to calculate consider boats for time periods before the arrival of Columbus to America...
Jan
21
comment How do I make a SHP file from waypoints?
You are right, nevertheless the gpx folder in my unit shows several gpx files, which can be confusing, the advantage of using EasyGPS is that shows all the information living on your gps unit at once. You can even select and delete things that you do not want in your final gpx file.
Jan
5
comment Isolate features within buffer of another feature - QGIS
The buffer is a polygon layer, try cliping the pipes layer with the buffer layer
Dec
22
comment QGIS OpenLayers 3 Google Maps not zooming
I have the same behavior. Working with anything else but google layers works ok
Dec
4
comment Reprojecting between NAD27 and WGS 84 part III
I want to let you know that the online tool works for points, nevertheless they have a paid product called IRIS that could work to transform layers, not only point by point between nad 27 and other coordinate systems. This product is a spatial information visualizer with some GIS capabilities. I was fortunate to grab a copy of it and I will make some experiments with it.
Dec
4
comment Reprojecting between NAD27 and WGS 84 part III
The INEGI (TRANINV) on line tool works to make translations between NAD27 and ITRF92, I get 500029.111572mE, 2100624.194940 mN. The difrerence is about 3m. The article you mention has a 7 parameter transformation but for ITRF92 epoch 1988.0 and NAD27. In the thread they say there are no known parameters for transformation between ITRF and WGS84.
Dec
4
comment Reprojecting between NAD27 and WGS 84 part III
First, thanks for your time, and I just want to tell you that I checked the EPSG registry and the parameters are he same as the ones in the links mentioned above. So in this sense I will mantain my custom crs to make transformations between NAD27 and WGS datums
Dec
3
comment Reprojecting between NAD27 and WGS 84 part III
The same info here iho.int/iho_pubs/standard/S60_Ed3Eng.pdf
Dec
3
comment Reprojecting between NAD27 and WGS 84 part III
I get the values from earth-info.nga.mil/GandG/publications/tr8350.2/wgs84fin.pdf appendix B.6-5., es.scribd.com/doc/2618870/ArcGIS-Transformations and resources.arcgis.com/en/help/main/10.1/003r/pdf/… page 53. As you can see the parameters I mention are only valid for Mexico
Dec
2
comment CRS reprojection
take in to account this: gis.stackexchange.com/questions/123069/…
Nov
27
comment Misplaced Google Maps with OpenLayers plugin in QGIS?
unibasil solution works
Nov
25
comment What is the fastest way to digitize features on a map?
The only partial solution I know is a paid one, R2V...