[Qgis-developer] Large raster (ecw) identify very long

[haubourg]

Hi all, 
I'm ready to support developpement now, so let's undig a topic discussed
previously here: 
http://hub.qgis.org/issues/4594 http://hub.qgis.org/issues/4594 

Identify for very large ecw (from 1 to 100 Go - 1 080 000 * 1 090 000
pixels) is extremely long (more than 1min) and results to memory leak.  Very
often, this only gives a useless RGB info because ecw are orthophotos or
topographic scans. 

This is a problem if identify mode queries all layers under mouse clic. 

1 - Memory leak can be solved by disabling Gdal cache for ecw says Nathan.*
Do you confirm ? Can you give more details so that I write a contract for
it? *

2 - *I would also like to add a behaviour to handle very long response time,
I would really like to have your feedback on it:*
     - Option 1 : Disable identify for very large raster layers in project
properties when raster is loaded. Keep QGS properties if raster is loaded
when opening a project file. Should we add options to configure that in
general options (" Disable very large raster identify " + "raster size
threshold")
     - Option 2 : Offer a checkbox in identify mode options  that could be
named "disable raster identify" 
     - Option 3 : Considering it's a very particular problem for huge ecw
users and let's make a plugin that deactivates identify for big raster.   I
must say I don't vote for here because most french public user I know are
using big ecw, and I think it might be harder and more expensive to do this
from python.. (and adds a python plugin to load, adds a thing more to handle
on enterprise config.. ) 

*I vote for Option 1*

Thoughts guys? 

(And welcome to Victor by the way, congratulations!)




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