Hi All, I have been working with a client that previously has been using ArcGIS for digitizing areas in the field on tablet laptops. Due to some frustrations with ArcGIS and ArcPad we went ahead and implemented a simple python plug-in that is based on the stream digitizing python plug-in, but adds a (csv file) configure simple custom form with prefilled drop down boxes. The whole things works great. Except one issue is that using compressed imagery such as ecw or *.sid images the speed of the application is pretty slow when digitizing (compared to ArcGIS).
Thus I have some questions for ideas or input on this. I am assuming that the speed in QGIS totally depends on the driver used for the ecw and .sid images - which as I understand is the ERMapper /Erdas driver. Is there anything that could be done that the stream digitizing of polygons (which itself without compressed imagery is blazing fast for shape files) that can be done that one does not suffer such big performance hits when using a compressed image as a background... As a work around I recommended to the client to use non-compressed imagery such as tiff - which when it has overviews is performing really well. However that means bigger storage space needed and the need to decompress the imagery and add overview, which we can use some gdal scripts for ....but still we would like to avoid these steps if possible. Thus, this is just to see if there options to optimize anything or there is nothing at this point that can be done to have better performance with compressed imagery. Also is there anybody that could report on how the speed for other formats such as JPEG2000 compares to ecw to MrSID (other formats)? Anyone ? Thanks a lot Cheers Karsten Vennemann Principal Terra GIS LTD www.terragis.net _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
