[Qgis-user] GRASS and UK LIDAR

[Dave Marshall]

Alex,

Many thanks for the quick response. That would explain why I see the
message to select a different CRS when I load these files into
later versions of QGIS but all the work I do generates UK Ordnance Survey
grid references so I have to use the 27700 projection or one that will
generate the exact same numbers. Perhaps I just have to live with the old
version.

Cheers,

Dave

On Mon, 8 Feb 2021 at 21:36, Alexis R.L. <alroyliz0 at gmail.com> wrote:

> PROj might have changed and your file projection is unsupported anymore.
> Transfer your layer to something less specific.
>
> Alex
>
>
> Le lun. 8 févr. 2021 à 14:57, Dave Marshall <43carnaby at gmail.com> a
> écrit :
>
>> Hello,
>>
>> I use QGIS 3.4 to visualise LIDAR tiles from the UK which use EPSG:27700
>> as the CRS. I put height contours on the images using the r.contour feature
>> in GRASS. This works extremely well. I have tried a couple of times to move
>> to a more up-to-date version of QGIS but in each case, the version of
>> r.contour associated with later versions does not work. These later
>> versions seem to require some sort of co-ordinate transformation on opening
>> the LIDAR files (I think to EPSG:4326) and I wonder if this is part of the
>> problem. Running r.contour generates an error message which seems to
>> suggest it does not recognise or cannot work with the CRS being used (there
>> is a reference to Airy Spheroid).
>>
>> What I would like to do is to be able to use a more up-to-date version of
>> QGIS but with the same version of GRASS which I get when I use 3.4. This
>> version would seem to be 7.6.1 rather than 7.8.5.
>>
>> There is a similar contour feature in QGIS under \Raster\Extraction but
>> this does not allow the specification of height ranges which is essential
>> for the work I am doing to avoid the routine from taking a very long time
>> to run.
>>
>> Any help or advice would be much appreciated,
>>
>> Dave Marshall
>> _______________________________________________
>> Qgis-user mailing list
>> Qgis-user at lists.osgeo.org
>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-user/attachments/20210208/f809c956/attachment.html>