Have you looked at the spatial applications available in R. It sounds like you have a lidar data set yes? R has a bunch of packages that could help, gstat, spatstat, maptools, sp, etc have a look at
http://wiki.r-project.org/rwiki/doku.php?id=tips:spatial-data One option I can think of, but cant remember how to do it is the following. Sometimes when interpolating lidar points (or any for that matter) it is useful to remove some points from your data for validation later on. typically one would remove 5 or 10% of the data and use this to validate the final surface. So you would then sit with the modelling data containing 90% of the original data and your validation data containing 10% of the original data. The removal is usually done randomly and would therefore allow you to retain the structure of your original data. As I said earlier I cant exactly remember how this is done, but the link should give you a good start. HTH Wesley Wesley Roberts MSc. Researcher: Earth Observation (Ecosystems) Natural Resources and the Environment CSIR Tel: +27 (21) 888-2490 Fax: +27 (21) 888-2693 "To know the road ahead, ask those coming back." - Chinese proverb >>> <nicholas.g.lawre...@mainroads.qld.gov.au> 02/26/09 6:57 AM >>> > nicholas.g.lawre...@mainroads.qld.gov.au wrote: > > A client has a very large (millions of records) ascii file consisting > > solely of x,y,z co-ordinates. > > > > They would like to reduce the number of records by weeking out points that > > are too close to each other. > > > > Can GDAL or OGR weed out 3D points based on proximity to each other? > > A job for GMT's blockmean or blockmedian. > Joaquim Luis Okay, I downloaded the Manpages. My initial reading is that blockmean and blockmedian work by averaging the values. My client says that they want the resulting data points to be a subset of the original data points, that is the process should delete points, not re-calculate new ones that are an average. Is this still do-able? Is there a specific option I should be looking at? Regards, nick *********************************************************************** WARNING: This e-mail (including any attachments) may contain legally privileged, confidential or private information and may be protected by copyright. You may only use it if you are the person(s) it was intended to be sent to and if you use it in an authorised way. No one is allowed to use, review, alter, transmit, disclose, distribute, print or copy this e-mail without appropriate authority. If this e-mail was not intended for you and was sent to you by mistake, please telephone or e-mail me immediately, destroy any hardcopies of this e-mail and delete it and any copies of it from your computer system. Any right which the sender may have under copyright law, and any legal privilege and confidentiality attached to this e-mail is not waived or destroyed by that mistake. It is your responsibility to ensure that this e-mail does not contain and is not affected by computer viruses, defects or interference by third parties or replication problems (including incompatibility with your computer system). Opinions contained in this e-mail do not necessarily reflect the opinions of the Queensland Department of Main Roads, Queensland Transport or Maritime Safety Queensland, or endorsed organisations utilising the same infrastructure. *********************************************************************** _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev -- This message is subject to the CSIR's copyright terms and conditions, e-mail legal notice, and implemented Open Document Format (ODF) standard. The full disclaimer details can be found at http://www.csir.co.za/disclaimer.html. This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. MailScanner thanks Transtec Computers for their support. _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
