Tag Info

Hot answers tagged

9

For a local solution, GRASS can be scripted to do this: # extract raster values at our points # use cubic convolution for interpolation between DEM locations v.drape in=my_pts out=pts_srtm_elev type=point rast=srtm_dem method=cubic I ran an extended version of this for one of my use cases and performance of v.drape was no issue at all.


4

If you want realistic data, then you might be able to make use of a solution that was posted over at Are the public domain vehicle tracks available?: The OSM magicians have released a lot of GPS tracks - its "GPX Planet" Note that there are two formats: just the points, and the GPX tracks. You presumably want GPX tracks.


4

SRTM data is easy to download for a given area, I've use this site in the past. The files aren't huge, and you can get them as georeferenced TIFFs. Downloading the whole world might take a while, but a couple of tiles covers a pretty large area. The issue you might have is with horizontal resolution, which is about 90 metres for most of the world, and the ...


3

I don't know much about gpsbabel, but here are a few examples with OGR: if you just need an approximation, you can use: ogrinfo -al -so infile.gpx Which will give you the binding box. Similarly, you can use ogr2ogr to pull out geometries which overlap a spatial extent with -spat: ogr2ogr -spat xmin ymin xmax ymax filtered.gpx infile.gpx If binding ...


3

It sounds like you need this as a generic solution, i.e. having all the world's elevation data available to you for any track you want to process, hence not wanting to store all the CGIAR data locally; the gpsvisualizer.com mentioned above (@Llaves) may be your best bet. If you don't need high resolution, the GTOPO data set (1km grid) is only ~300MB for the ...


2

I wonder if you are able to download data, in any case this link describes how to connect a garmin usb gps in Qgis http://nickmcw.wordpress.com/2010/07/30/quantum-gis-using-a-usb-gps-device/ As everyone else has told you, a little bit of more information could be useful in order to help you.....


2

First you should specify what kind of horizontal/vertical precision you would be satisfied with. But let's look at this from a practical perspective: Each SRTM3 tile has 1200x1200 cells, each cell is a two-byte integer value representing the elevation in meters. That's around 2.75 MB of raw uncompressed data. There are 14042 SRTM3 tiles. That's cca. 38 GB ...


1

I haven't used GPSBabel. Based on the list of supported formats, I would try to use csv (csv) or universal csv (unicsv) or kml. If the file format supports different formats for the latitude/longitude values, try to use a signed decimal degree format, +/-DDD.ddddd.


1

It's not a matter of the gdb format, but the CSV output driver of GPSbabel. If you select that, only waypoints are available for conversion, and additional information gets dropped. See http://www.gpsbabel.org/htmldoc-development/fmt_csv.html for more details. On this page you will find a note that the gdb format is undocumented. You better select GPX ...


1

I think the instruction you followed were meant for "old" GPS devices. With a GPSmap 62, you do not have to use gpsbabel at all to download your data. They are already stored as gpx-files on the device. After plugging the GPS device, use your file browser and navigate to your gpx files on the device, and dragndrop them into the map canvas of QGIS. There ...


1

I can't say why it is not working with the readGPS function in the maptools package, but I was able to loop through the files reading in the data using the readOGR function in the rgdal package. setwd("C:\\Documents and Settings\\Owner\\Desktop\\R_test") library(rgdal) #I just saved my text files in the above directory myfiles <- list.files() #this ...



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