I hope to help anyway I can ENT's with the LIDAR just ask me: 803-673-7364 I'm there on my off day in the park walking around. I think now going to that slough that got the height and shoot straight up under some of the tree to see the height. Marcas
On Mar 7, 6:50 pm, DON BERTOLETTE <[email protected]> wrote: > Paul/Will- > LIDAR is new enough that it still takes judgement, and ground-truthing. One > of the ways that LIDAR users try to improve their analysis is to have random > (or systematic) plots of high density LIDAR (cost- and data > storage-prohibitive for large areas). High density LIDAR has about 4 > pie-plate sized 'hits' per square meter and can be depended on to obtain > accuracy in the .5 to 1.5 foot height data. As to ground level accuracy, > LIDAR can be confused when going in and out of swamp, as Paul explained. > He's correct in his comment that there are other sources available to > determine ground level data, although to get good accuracy the two layers > need calibration and adjustment. I am glad that NPS folks were interested in > using your climbing/sin-sin height data to ground-truth theirs. > -Don > > > > > From: [email protected] > > To: [email protected] > > Subject: [ENTS] Re: Lidar data availability and possible application > > Date: Sat, 7 Mar 2009 13:11:47 -0600 > > > Will, > > > I've been thinking about the excessively high 150' canopy in the swampy part > > of Congaree. I can understand LiDAR underestimating height due to > > reflection intensity on small limbs, but gross overestimating would have to > > be due to an incorrect ground surface approximation. The cypress/tupelo > > swamps have a unique condition of partial or complete standing water under > > trees. Water can provide very high quality reflections such that multipath > > errors could be possible. The laser could reflect off the water back to the > > plane, but also reflect off the water then off the understory or large > > trunks back to the water and then back to the plane, providing an estimate > > of the ground level that is actually significantly beneath the actual > > surface. I would suspect that if this were occurring, that the LiDAR ground > > surface plot would probably not be as flat as expected there (only a few > > feet of variation would be typical) and would be far lower than the known > > elevation (depending upon the sample angle, up to half the difference of the > > measured canopy height vs. real height). If anyone still has access to this > > data, it would be simple to check it out. The flood plain levels are > > probably well known. > > > Paul > > ----- Original Message ----- > > From: "Will Blozan" <[email protected]> > > To: <[email protected]> > > Sent: Saturday, March 07, 2009 11:34 AM > > Subject: [ENTS] Re: Lidar data availability and possible application > > > > Paul, Bruce, > > > > I briefly looked at the LiDAR data at Congaree last visit and found some > > > glaring "errors". The highest forest canopy was generally the pine groves > > > but one tupelo/cypress swamp had a 150'+ canopy over dozens of acres. That > > > is simply not possible. > > > > Will F. Blozan > > > President, Eastern Native Tree Society > > > President, Appalachian Arborists, Inc. > > > -----Original Message----- > > > From: [email protected] [mailto:[email protected]] On > > > Behalf Of Paul Jost > > > Sent: Saturday, March 07, 2009 12:23 PM > > > To: [email protected] > > > Subject: [ENTS] Re: Lidar data availability and possible application > > > > Bruce, > > > > I don't expect LiDAR to measure tree heights very accurately, especially > > > in > > > free USGS data. I hope that it can help locate potential tall trees that > > > can be found on the ground and then measured accurately by ENTS methods. > > > It > > > > could help focus searches on large public lands that would otherwise take > > > many lifetimes to effectively explore. > > > > Paul > > > > ----- Original Message ----- > > > From: "Bruce Allen" <[email protected]> > > > To: <[email protected]> > > > Sent: Saturday, March 07, 2009 6:49 AM > > > Subject: [ENTS] Re: Lidar data availability and possible application > > > > In the Congaree, Lidar doesn't seem to pick up the highest small > > > branches. If you looked at the Park Services canopy height map it > > > just doesn't seem to pick up the max height effectively. > > > > Bruce > > > > On Fri, Mar 6, 2009 at 11:32 PM, Paul Jost <[email protected]> wrote: > > > >> Gary, > > > >> With regards to the application of LiDAR data to our tall tree searches, > > >> when I've worked out the bugs as much as reasonably possible, I'll post > > >> some > > >> screen shots and some info on the process so that others can do the same > > >> thing for FREE!! It should be in the next week or so.... > > > >> Paul > > > >> ----- Original Message ----- > > >> From: <[email protected]> > > >> To: <[email protected]> > > >> Sent: Friday, March 06, 2009 8:26 PM > > >> Subject: [ENTS] Re: Lidar data availability and possible application > > > >>> Thanks Paul. I am enjoying your posts. > > > >>> Gary > > >>> Sent via BlackBerry from T-Mobile > > > >>> -----Original Message----- > > >>> From: Paul Jost <[email protected]> > > > >>> Date: Fri, 06 Mar 2009 18:45:03 > > >>> To: <[email protected]> > > >>> Subject: [ENTS] Re: Lidar data availability and possible application > > > >>> Gary, > > > >>> I'm using free LiDAR data from the USGS product page with free FUSION > > >>> software from the U. of Washington. > > > >>> Paul > > > >>> ----- Original Message ----- > > >>> From: <[email protected]> > > >>> To: <[email protected]> > > >>> Sent: Friday, March 06, 2009 6:34 PM > > >>> Subject: [ENTS] Re: Lidar data availability and possible application > > > >>>> Paul, > > > >>>> Just joining the list after a hiatus and I am interested in what you > > >>>> are > > >>>> doing. I have ArcGIS 9.3 and now a Magellan Mbile Mapper 6. Did you buy > > >>>> the LIDAR? > > > >>>> Gary > > >>>> Sent via BlackBerry from T-Mobile > > > >>>> -----Original Message----- > > >>>> From: Paul Jost <[email protected]> > > > >>>> Date: Fri, 06 Mar 2009 18:28:27 > > >>>> To: <[email protected]> > > >>>> Subject: [ENTS] Re: Lidar data availability and possible application > > > >>>> Josh, > > > >>>> I've been working on the Wright Creek LiDAR data and need to finish > > >>>> working > > >>>> on optimizing the generation of the bare earth topographical layer from > > >>>> the > > >>>> LiDAR data. Preliminary work shows quite a few trees in the 140's, a > > >>>> few > > >>>> in > > >>>> the 150's, and possibly one around 171 feet tall. This software is > > >>>> pretty > > >>>> cool. I can measure individual trees, color by tree height, etc. > > > >>>> I need to verify if any are outliers or noise but would like to ground > > >>>> check > > >>>> some. I also haven't checked out much of the creek yet. Did you GPS any > > >>>> of > > >>>> the trees when you were there? If so, can you enter a user coordinate > > >>>> system in your GPS? I'm working in State Plane for NC in feet, the form > > >>>> that the LiDAR data comes in. I can give you info on how to set up user > > >>>> coordinate systems in your GPS if you used it there. Otherwise, I'll > > >>>> have > > >>>> to find a way to convert the coordinates myself - easier to do with the > > >>>> more > > >>>> expensive GIS software. > > > >>>> Paul > > > >>>> ----- Original Message ----- > > >>>> From: "Josh Kelly" <[email protected]> > > >>>> To: "ENTSTrees" <[email protected]> > > >>>> Sent: Monday, March 02, 2009 3:56 PM > > >>>> Subject: [ENTS] Re: Lidar data availability and possible application > > > >>>>> Paul, > > > >>>>> Let me know how using the LIDAR data around Santeetlah goes. If you > > >>>>> find any great trees, I could ground truth them next time I return to > > >>>>> the area. I'm quite sure there are 160' poplars in the area (second > > >>>>> growth) and maybe some 170's. > > > >>>>> Josh > > > > -- > > > Bruce P. Allen > > > Springfield, NH > > _________________________________________________________________ > Windows Live™: Life without > walls.http://windowslive.com/explore?ocid=TXT_TAGLM_WL_allup_1a_explore_032009 --~--~---------~--~----~------------~-------~--~----~ Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected] -~----------~----~----~----~------~----~------~--~---
