shrug-l: Building Footprint Generation

Joel_Cusick at nps.gov Joel_Cusick at nps.gov
Mon Dec 29 16:22:53 EST 2008


Eric,
A bit off technique, but use of GPS with the Square Building Script in
Alaska Pak works great.

This technique will not address automation of building footprints from a
cubicle, but here in Alaska, with sparse imagery and frequently poor
resolution datasets, were resorting to on-ground GPS data collection
methods.   Combining submeter GPS, and software (TerraSync or ArcPad) that
allows average vertices along a line (the two nodes making up a line), we
can generate excellent footprints without the errors any Ortho user battles
- like building lean and shadows.  Its fast and with well-trained GPS users
is extremely accurate.  This GPS method is limited to square or simply
constructed rectangular buildings.

Ingredients:
1) Data dictionary or ArcPad form with a line feature.  2 attributes:
Building_Width (ft or meters - numeric) and Building_Side (domain values
Left ; Right)
2) AlaskaPak script
http://science.nature.nps.gov/nrgis/applications/gisapps/gis_tools/8x/alaskapakv2_2ChangeLog.aspx
 .  The Square Building script part of Alaska Pak that ingests the line
feature and constructs a perpendicular footprint of a building from the GPS
generated line.

Field Method:
User collects a set of GPS positions (vertices) on the first corner of a
building.  Use of offsets minimizes multipath.  Mapper than occupies the
second corner of the building using a set of GPS positions (vertices).
Mapper populates Building_Width with the taped width of building, and fills
in "Left or Right" for the Building_Side attribute that corresponds to the
side which the building occupies to the mappers perspective.

PostProcessing:
After the field, Use AlaskaPaks "Square Building" script on the GPS line
feature that generates a polygon representing the building footprint.

Combined with on-ground photos of primary entrances (tagged with a GPS
point), a photo of building and footprint poly can be generated very
effieciently and accurately.
******************************************************
Joel Cusick
National Park Service
GIS Specialist/Alaska Regional Office
240 West. 5th Avenue, Anchorage, AK - 99501
(907) 644-3549  joel_cusick at nps.gov
+61 13' 01.28", -149 53' 10.58";  (NAD83 CORS96)
******************************************************


                                                                           
             "Tripp Corbin"                                                
             <tcorbin at keckwood                                             
             .com>                                                      To 
             Sent by:                  <Eric_Songer at URSCorp.com>, "GIS     
             shrug-l-bounces at l         Users Forum"                        
             ists.dep.state.fl         <gisusersforum at eciolist.state.ar.us 
             .us                       >, <shrug-l at lists.dep.state.fl.us>, 
                                       "Oklahoma GIS Community"            
                                       <okgis at orion.csa.ou.edu>            
             12/29/2008 11:31                                           cc 
             AM                                                            
                                                                   Subject 
                                       RE: shrug-l: Building Footprint     
                                       Generation                          
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




Eric,
In Georgia the Tax Assessors store sketches of buildings in their CAMA
systems.  While not entirely georeferenced they are linked to specific
parcels. So we have been able to extract that sketch from the CAMA System
and have it placed in the correct parcel.  That is about as automated a
method as I have seen. Users still have to come and move the building
sketch to match the aerials.

Tripp Corbin, MCP, CFM, GISP
Vice President, GIS/IT
ESRI Authorized Instructor
Keck & Wood, Inc.
(678) 417-4013
(678) 417-8785 fax



From: shrug-l-bounces at lists.dep.state.fl.us
[mailto:shrug-l-bounces at lists.dep.state.fl.us] On Behalf Of
Eric_Songer at URSCorp.com
Sent: Monday, December 29, 2008 3:26 PM
To: GIS Users Forum; shrug-l at lists.dep.state.fl.us; Oklahoma GIS Community
Subject: shrug-l: Building Footprint Generation



Okay,

I apologize. I just sent out a message with the wrong Subject Line. So, I'm
resending. Sorry for the double message.

I've heard of automated building footprint algorithms or automated process
using aerial imagery. Does anyone know how automated building footprint
generation works? Or even better does anyone have experience using it? Do
you need lidar or raw elevation data?

Any help would be greatly appreciated.

Thanks,

Eric Songer
URS Corporation
1625 Summit Lake Drive
Tallahassee, FL 32317
Direct: 850.402.6327
Main: 800.842.9671 ext. 327
eric_songer at urscorp.com



                                                                            
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