On Sun, 1 Nov 2020 17:26:46 -0500, Garth Fletcher <ga...@jacqcad.com> wrote:
Just a side note. If I understand it correct, this procedure will store in attribute table (as a temporary or permanent attribute) the coordinates as they are at the time it is stored. If a point is moved through edition that value will not be updated automatically. It will be necessary to store the new value in the table with the described procedure. > My experience is with .gpx files generated by a Garmin eTrex-20. > > When I use QGIS's Data Source Manager to open a and Add a .gxp file I > see several different layers: > Tracks > Track Points > Routes > Route Points > Waypoints > > The one you want is "Track Points" because it contains all the > individual points which collectively make up the tracks. "Tracks" > only contains link(s) to the various tracks that have been recorded - > it usually only contains one item unless you have saved multiple > tracks. > > You may also be interested in "Waypoints" if you've recorded specific > waypoints on your GPS. > > So Add the layers of interest (Track Points and maybe Waypoints) > > Because a .gpx file is "input only", your first step needs to be to > to right-click on the layer, select Export > Save Features As... > > This will let you save the layer in a form that can be edited. Keep > this new layer (you can remove the original .gpx layer) > > The layer's Attribute Table contains fields for all sorts of > attributes, but NOT including the location (Lat,Long) data which is > stored separately. > > So to be able to make your own location based calculations you want to > copy the point locations into new fields in the Attribute Table. > > With the layer selected, select the Field Calculator (Abaccus icon in > toolbar) > check Create a new field > enter a name, e.g., "Latid" > set Output field type to Decimal number (real) > set Output field length to 10, Precision to 6 > type "$y" in the Expression window below > {$y is the location's Y axis, i.e., its latitude} > click OK > the first time it may warn you that the layer is not in edit mode and > than proceding will turn on edit mode - this is fine > > Now repeat for a 2nd field, using a different field name and > expression "Longid" and $x > > Now when you open the layer's Attribute Table you will see 2 new > fields at the right which contain the point's Latid and Longid > values... > > Save the layer if you want to keep these additions. > > > On 11/1/20 2:17 PM, J. M wrote: > > Hi again Garth, > > > > Well I parked this problem and only just came back to it. I may > > have missed something, but when I create the new fields you > > suggested in the Track they contain no information. Is this a very > > advanced procedure? It seems like something quite basic, but > > perhaps I've underestimated it (as I usually do with QGIS!). > > > > Kind regards, > > Jimi. > > > > On Fri, Sep 11, 2020 at 11:51 AM J. M <jimimc...@gmail.com > > <mailto:jimimc...@gmail.com>> wrote: > > > > Hi Garth, > > > > Thanks a lot for the very complete answer! I'll give it a go as > > soon as I resolve an unrelated Ubuntu problem. I hadn't realised > > that GPX data wasn't automatically visible in Properties, and that > > fields had to be created. > > > > Kind regards, > > Jimi. > > > > On Fri, Sep 11, 2020 at 4:26 AM Garth Fletcher > > <ga...@jacqcad.com <mailto:ga...@jacqcad.com>> wrote: > > > > On 10 Sep 2020 at 20:12, J. M <jimimc...@gmail.com > > <mailto:jimimc...@gmail.com>> wrote: > > > I can successfully import .gpx files into QGIS, and they > > > are > > visible and > > > can be clustered in new groups (waypoints, tracks and > > > routes > > appear as > > > independent layers). The problem I'm having is that I > > > can't > > seem to find > > > any way to access the data about the routes (distance, > > > time, > > etc) which is > > > clearly visible in the app I used to create the tracks > > > > The GPX file contains a number of fields whose contents you > > can see / > > access in the layer's Attribute Table > > right-click on layer and choose Open Attribute Table > > > > However, these are only the extra fields in the GPX records > > but NOT including the x,y coordinates (Long,Lat) > > > > To access the later, use the Field Calculator > > select the layer > > click on Open Field Calculator icon (Abaccus) in the > > menu bar which is next to the Open Attribute Table icon in menu, or > > in Processing > GDAL > Vector Table > Field Calculator > > > > create new fields, called Lat and Long, as decimal numbers > > and enter the expression $X or $Y (see Geometry > for > > details) When you click OK, the new fields will be appended and > > filled in with the right values. > > > > You can then access them in the layer's Attribute Table. > > > > With those 2 extra fields you essentially have access to > > everything that was recorded in the GPX file. > > > > You can also use Field Calculator to add more fields and > > populate them with calculation results. > > > > As an aside, Field Calculator cannot create new fields in > > the GPX file; instead it creates them as temporary virtual fields. > > > > A better approach is to first save the data in a shape file > > right-click on layer, choose Export > Save selected > > features then open that file instead of the original GPX. > > Field Calculator will add new fields to that format. > > > > Cordially, > > -- > > Garth Fletcher > Roxo -- ---------------- Non luctari, ludare -------------------+ WYSIWYG Fernando M. Roxo da Motta <pe...@roxo.org> | Editor? Except where explicitly stated I speak on my own behalf.| VI !! PU5RXO | I see text, ------------ Quis custodiet ipsos custodes?-------------+ I get text! _______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user