Regina, there is no real limits on the number of bands but I tend to agree with Paul: you can convert a lidar coverage to a grid but this is a lossy operation like converting a vector coverage to raster. The amount of information you lose is dependent on the resolution of the target raster and there is no perfect resolution (only 0 which is impossible).
Pierre From: [email protected] [mailto:[email protected]] On Behalf Of Paragon Corporation Sent: 8 juillet 2010 12:23 To: 'PostGIS Users Discussion' Subject: Re: [postgis-users] lidar: what is the recommended wayof storing/indexing Okay since everyone is providing their suggestions, let me provide my less than educated suggestion based on my fuzzy assumption of how Lidar is structured. Why don't you just use the new WKT Raster (PostGIS raster storage)? It allows you to store multiple bands per pixel. I think you might even be able to use GDAL to load the Lidar data right in ot the PostGIS raster storage format given this bug fix. http://trac.osgeo.org/gdal/ticket/3523 So I'm imaging your z, range, target number, reflectance you would store as separate raster bands. Pierre and Jorge can correct me, but I don't think there is a limit on the number of raster bands you can store per raster tile http://www.postgis.org/documentation/manual-svn/RT_reference.html With that you can do spatial intersects queries to pull out the different band values with http://www.postgis.org/documentation/manual-svn/RT_ST_Intersection.html or http://www.postgis.org/documentation/manual-svn/RT_ST_Value.html The meta data function would be useful for letting you know how many bands you have etc. http://www.postgis.org/documentation/manual-svn/RT_ST_MetaData.html Hope that helps, Regina ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of Peter Baumann Sent: Thursday, July 08, 2010 9:32 AM To: PostGIS Users Discussion Subject: Re: [postgis-users] lidar: what is the recommended wayof storing/indexing Indeed, a column store for arrays is usually quite ;-) inefficient. Let me point you to the rasdaman array DBMS which plugs into PostgreSQL and offers an optimized array query language on top. See www.rasdaman.org<http://www.rasdaman.org>. -Peter Paul Ramsey wrote: Oh, actually one-row-per-point is a bad idea, because the size of lidar sets mitigates against that. Putting them into multipoint collections of 50 or 100 points is better. But that implies preprocessing things a bit to find good patches. In generally, there's a lot of tooling needed to do this well, I fear. P On Thu, Jul 8, 2010 at 6:27 AM, Paul Ramsey <[email protected]><mailto:[email protected]> wrote: There is no recommended way right now. It's a core development activity I'd love to have funded... :) http://opengeo.org/products/coredevelopment/postgis/pointclouds/ In the meanwhile a approach might be to put the x/y/z into a postgis geometry and stuff the rest of the data into an array of doubles in another column. Your app would need to know which array element was which kind of data, but you'd still have it all available. P. On Thu, Jul 8, 2010 at 2:53 AM, Biddy <[email protected]><mailto:[email protected]> wrote: Hi everyone, is there a recommended way of storing lidar data in postgis? In particular, I am interested in not just storing long, lat, alt but also keeping all the raw data (for example range, target number, reflectance, etc.) Regards, B. _______________________________________________ postgis-users mailing list [email protected]<mailto:[email protected]> http://postgis.refractions.net/mailman/listinfo/postgis-users _______________________________________________ postgis-users mailing list [email protected]<mailto:[email protected]> http://postgis.refractions.net/mailman/listinfo/postgis-users -- Dr. Peter Baumann - Professor of Computer Science, Jacobs University Bremen www.faculty.jacobs-university.de/pbaumann<http://www.faculty.jacobs-university.de/pbaumann> mail: [email protected]<mailto:[email protected]> tel: +49-421-200-3178, fax: +49-421-200-493178 - Executive Director, rasdaman GmbH Bremen (HRB 147737) www.rasdaman.com<http://www.rasdaman.com>, mail: [email protected]<mailto:[email protected]> tel: 0800-rasdaman, fax: 0800-rasdafax, mobile: +49-173-5837882 "Si forte in alienas manus oberraverit hec peregrina epistola incertis ventis dimissa, sed Deo commendata, precamur ut ei reddatur cui soli destinata, nec preripiat quisquam non sibi parata." (mail disclaimer, AD 10xx)
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