That looks really good. Very useful for tracing buildings because there is no angle distortion. You can even pick out the differences between the main block of a building outline and the lower parts such as single storey extensions and garages. One drawback is that vehicles show up but they tend to be smaller than most structures.
Be interesting to see a semi-transparent version over an aerial image to see if the two combined make tracing very easy or just confusing. Cheers Andy -----Original Message----- From: Phil Endecott [mailto:spam_from_os...@chezphil.org] Sent: 24 September 2015 18:41 To: talk-gb@openstreetmap.org Subject: Re: [Talk-GB] Environment Agency LIDAR datasets OGL licensed now available Chris Hill wrote: > Suitably processed this could provide a source of building outlines. Yes, I think it could be very useful for that. I've had a play and rather than doing shaded relief I've just converted the height directly into a grey shade. I've then applied ImageMagick's edge detection filter. Here are a couple of fragments near Manchester taken from the 25cm resolution data; in each case the first image is the direct height-to-grey and the second is edge-detected: http://chezphil.org/tmp/lidar1.png http://chezphil.org/tmp/lidar1_ed.png This is at SJ 8099, or maybe search for Chaseley Road to find it on a map. You could easily trace building outlines from this and determine roof shapes and could measure building heights by subtracting roof from ground, with some suitable tool. You could also trace trees and some walls. http://chezphil.org/tmp/lidar2.png http://chezphil.org/tmp/lidar2_ed.png This is SE of the last one at SJ 8198. The gasometers (presumably!) are at the junction of West Egerton Street and Liverpool Street. I find it interesting that you can count the number of ridges in the large warehouse roofs. You can also easily identify carparks! How would people find this for tracing compared to photo imagery? Cheers, Phil. _______________________________________________ Talk-GB mailing list Talk-GB@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-gb ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2015.0.6140 / Virus Database: 4419/10688 - Release Date: 09/23/15 _______________________________________________ Talk-GB mailing list Talk-GB@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-gb
