There are always potential sources of errors in any data set. Subfoot accuracy can be expected from small beam widths with more than one sample per square meter. Dense forest canopy can prevent accurate modeling of the bare earth beneath it. Large flocks of large migratory birds might affect it. Humps and rises may not appear in dense forested datasets. Improper filtering of ground data may cause gross errors in height data. I'm not sure how quickly the airborne GPS reacts to updrafts and downdrafts during the data taking flight. I'm sure there are other sources of errors. Ground verification will always be necessary. LiDAR won't replace field work, but could guide one to areas of high likelihood of success, definitely an improvement over random searches through large areas of old growth.
Paul ----- Original Message ----- From: "Bruce Allen" <[email protected]> To: <[email protected]> Sent: Saturday, March 07, 2009 11:40 AM Subject: [ENTS] Re: Lidar data availability and possible application Will, It may not be 150, but in our plot it seems to be consistently 120-130+. And these are young trees (for cypress <120 years old), few over 1 m, over 600/ha, high basal area- 70m2/ha. When I looked at the Parks canopy map, very few areas were over 100 feet tall. That just isn't accurate. Bruce On Sat, Mar 7, 2009 at 12:34 PM, Will Blozan <[email protected]> wrote: > > 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 > > > > > > > > > > -- Bruce P. Allen Springfield, NH --~--~---------~--~----~------------~-------~--~----~ 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] -~----------~----~----~----~------~----~------~--~---
