technical presentation documenting the process to classify land use at the cedarburg bog
DESCRIPTION
Cedarburg Bog, a large forested wetland that includes diverse species existing near their southerly limits, provides a unique setting in which to study long term ecological changes in response to land use and climate changes. Land cover changes can alter the amount and distribution of habitat available to organisms and this could, in turn, influence the movement of organisms and their ability to respond to a changing climate. We used a GIS to quantify patterns of land cover change by comparing a 1941 land cover map to a recent land cover map in order to explore patterns of land cover change within recent history. To create a historical land cover map, we scanned 1941 aerial photos to create digital images that were then georeferenced and joined into a photo mosaic. A simple land cover classification scheme was manually applied to the historical and recent imagery. Our preliminary results suggest two main changes on this landscape over the last 60 years. Suburban developments now occur on patches of former agricultural land, and roads associated with development have increased fragmentation. It also appears that forest cover has increased due to reduced logging and abandonment of agricultural lands. Cedarburg Bog remains a large, undisturbed wetland in an otherwise changing landscape. Changes in the surrounding landscape could increase the abundance of non-native species and favor the movement of organisms, native and non-native, within forested cover types.TRANSCRIPT
![Page 1: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/1.jpg)
Historical classification of land cover at the Cedarburg Bog
Jason Schroeder
CES major – UWM
1 credit BIO SCI 699 with Dr. Erica Young
![Page 2: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/2.jpg)
Introduction
Part of a study of long term ecological changes in Cedarburg Bog
Long term studies will measure land cover changes within Cedarburg Bog (in response to climate and land use changes)
Project looks at land cover classification during time points 1941 & 2000
![Page 3: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/3.jpg)
Introduction continued
Land cover classification can reveal wildlife and plant corridors Provide avenues for animals and invasive species
to and from the Bog
Comparison of two time points can provide insight into ecological changes Anthropogenic alteration of landscape
Farm abandonment Human settlement
![Page 4: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/4.jpg)
Project Objectives
Use historical aerial photographs to map land use changes in Cedarburg Bog and surroundings
Use GIS to classify land cover categories:1. Forest2. Agriculture3. Water4. Wetland
Identify major areas of land use changes and corridors surrounding Cedarburg Bog
![Page 5: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/5.jpg)
Methods
Georeferenced 1941 aerial photos in ‘ERDAS Imagine’ software package
Classified 1941 land cover
Compare land use changes between 1941 - 2000
![Page 6: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/6.jpg)
Georeferencing
Apply a coordinate system to raw photos Distorts raw image to fit projected coordinate
system Corrected for curvature of earth
Coordinate system allows for exact location of objects Allows for ‘mosaicking’ of aerial photos Classification, area determination, queries
![Page 7: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/7.jpg)
Georeferencing
1941 – raw unreferenced photo 2000 – georeferenced photo
![Page 8: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/8.jpg)
Ground Control Points
Create points in raw photo that mirror georeferenced photo (next slide)
20 – 40 points per photo
1941 – raw unreferenced photo
![Page 9: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/9.jpg)
Ground Control Points
2000 – georeferenced photo
Points in this photo mirror points in raw photo
Raw photo now has coordinate system imbedded
![Page 10: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/10.jpg)
1941 Raw Image No spatial
information
1941 GEOTIFF Coordinates imbedded
![Page 11: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/11.jpg)
Mosaic process Merge georeferenced photos to make a
seamless map
![Page 12: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/12.jpg)
Detail of Mosaic process: merging overlapping images
Overlap from two photos
![Page 13: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/13.jpg)
Software generates a “cutline”
Looks for pixels from each image that are similar to create seamless merge
![Page 14: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/14.jpg)
Seamless merge – finished mosaic
![Page 15: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/15.jpg)
Final mosaic – 15 photos merged together
![Page 16: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/16.jpg)
Automatic classification limitations with grayscale images
Grayscale colors limited (256 shades of gray) Land cover patterns with similar pixel shades
classified in same group Water & forest Agriculture & wetland
Water overrepresented Wetland underrepresented
![Page 17: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/17.jpg)
‘Supervised’ classification Blue: water
Green: forestTan: agriculture
By comparing this classification to the next slide, it is apparent that water is overrepresented - dark forest pixels are mistaken for water pixels.
![Page 18: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/18.jpg)
![Page 19: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/19.jpg)
Going forward
Manual classification of 1941 image More time effective More accurate
Provide a base map from which to compare changes
Compare to DNR WISCLAND land cover map (1992) or National Land Cover Dataset NLCD (2001)
![Page 20: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/20.jpg)
Animated GIF from 1941 - 2000
![Page 21: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/21.jpg)
1941
![Page 22: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/22.jpg)
2000Areas of major change:
![Page 23: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/23.jpg)
Conclusions
Automatic classification of grayscale images difficult and results in inaccurate results
Manual classification may take less time, provide more accuracy
1941 images can be compared to published WISCLAND or NLCD maps
Comparison of two time points shows that agriculture has decreased, forest and human settlement increased
Future results will be statistical
![Page 24: Technical presentation documenting the process to classify land use at the Cedarburg Bog](https://reader036.vdocument.in/reader036/viewer/2022081602/5553f022b4c90577468b46b6/html5/thumbnails/24.jpg)
Acknowledgements
Dr. Jason E. Mills and Dr. Erica B. Young
Department of Biological Sciences
University of Wisconsin-Milwaukee
References WISCLAND, http://dnr.wi.gov/maps/gis/datalandcover.html NLCD, http://www.mrlc.gov/mrlc2k_nlcd.asp