Dear Jonathan,
thanks for answering. Ive forgotten to tell you an maybe important- detail: Im working with a virtual raster catalogue which i built out of 875 .jpgs (4000x4000). Zoom to best scale (100%) ends in scale 1:668 (for one of the 875 tiles as well as for the virtual raster catalogue of the 875 tiles). So if I understand you right I have to calculate the 106x106 pyramide and smaller ones respectively level 37,5 and higher ones, right? Kind regards, Julian Schall Julian Schall Fürstenberg Forst Josefstraße 11 | 78166 Donaueschingen Mobil: + 49 (0) 178 / 547 666 0 Tel.: + 49 (0) 771 / 229 677 425 Fax: + 49 (0) 771 22 96 77 406 <http://www.ff-forst.de/> www.ff-forst.de | <http://www.tierfriedhof-sb.de/> www.tierfriedhof-sb.de Von: Jonathan Moules [mailto:[email protected]] Gesendet: Donnerstag, 12. Juni 2014 11:34 An: Julian Schall Cc: [email protected] Betreff: Re: [Qgis-user] QGIS: Reduction of resolution via pyramids only for defined scale range Hi Julian, You can specify at what levels pyramids are created. That's what the "resolutions" box on the right does. The problem is, knowing which levels you want. So if your data is a 4000x4000 tiff then it'll offer to create pyramids at: 2000*2000 1000*1000 500*500 250*250 125*125 63*63 I'm going to guess at the answer to your question - I believe what you need to do is the following: - Find out what the scale is for "Zoom to best scale (100%)" for the raster. For my raster it's 1:9,449 (yours will be obviously be different). - So the 2000x2000 pyramid will have a scale of 1:18898 (i.e. double 9449). So you wouldn't want that level. In this scenario you may want 1000*1000 - which would be for a scale of 1: 37796 (double 1:18898). So with some simple maths you can figure out which pyramid levels you want. I suppose it would be a good feature for QGIS to show scales rather than tile sizes in the "resolutions" box. I'll go open a feature suggestion for that one. Cheers, Jonathan On 12 June 2014 10:00, Julian Schall <[email protected]> wrote: Hello members of the mailing list, I would appreciate help on the following problem: I would like to improve the performance of a raster layer. Of course I can build pyramids for that purpose. But in the scale ranges from 1:1 to 1:25.000 I need maximum resolution and detail. In this scale range, the performance is sufficient even without pyramids. Ideal would be that the pyramids respectively the reduction of the resolution with improvement of performance is only applied to scales smaller than 1:25,000. Is this possible in QGIS? Thanks for helpful answers! Kind regards Julian Schall _______________________________________________ Qgis-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-user This transmission is intended for the named addressee(s) only and may contain confidential, sensitive or personal information and should be handled accordingly. Unless you are the named addressee (or authorised to receive it for the addressee) you may not copy or use it, or disclose it to anyone else. If you have received this transmission in error please notify the sender immediately. All email traffic sent to or from us, including without limitation all GCSX traffic, may be subject to recording and/or monitoring in accordance with relevant legislation.
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