[Qgis-user] large DEM not loading tiles correctly

[Patrick Dunford]

Hello

This is a raster format? and how large are the tiles?

I spend a lot of time working with raster files often a few thousand at 
a time. There doesn't seem to be a problem displaying them in Qgis 
unless they are Progressive Jpeg format, which in more recent years seem 
to have an issue with one of the third party libraries Qgis uses to 
import with.

On 29/09/22 00:32, Michael.Dodd via Qgis-user wrote:
>
> I am trying to put together the 50m uk DEM e.g. 
> https://www.data.gov.uk/dataset/835cf20a-8feb-4394-8b30-dcfe840ac13d/os-terrain-50-dtm 
> but it often does not work.  The data are supplied as thousands of 
> small tiles that takes ages to unpack and put into a folder to get 
> into qgis, however when you try to load the tiles some work and others 
> don’t and even the ones that do work and display fine sometimes don’t 
> merge to form large tiles and sometimes will form virtual rasters but 
> not merged files.  Basically it is a mess.  I suspect others have done 
> this successfully so any suggestions?
>
> It is particularly odd that some of the tiles will merge and others 
> won’t and that some won’t display if you ask it to load hundreds at a 
> time but if you just add them in a few at a time then they will load 
> and display (in addition to the hundreds already loaded). This 
> suggests various bugs assuming the original data are not in a whole 
> variety of slightly different formats (should all be .asc)
>
>
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