Methods

Blanchard Mountain is located south of Bellingham about ten miles. It is the one area in the Puget Sound where the Cascade Mountains meet with the Puget Sound. It is also the largest area of old growth forest situated near the Puget Sound. The area right now is DNR land and is slated to be logged in the near future. There are several groups of people that have come together to protect this mountain and they could use the help of individuals who have knowledge of GIS and its various capabilities. If this land is not turned into a designated park area it will be logged in the near future and the opportunity to save the area will be lost.

                 The data that has been collected so far for this project is a complex and long list. Satellite images are being used from the J-drive, this data is four different TM satellite images from four separate years. The vector data being used is a study area polygon, DNR land polygon, Skagit DNR land polygon, Whatcom DNR land polygon, Whatcom parcel polygon, and Skagit parcel polygon.

Four ten meter DEMs are being used. These are South Bellingham, Bow, Alger, and Lake Whatcom. These have also been used to create hillshades of each area. We decided early on in the project that we would organize our data in a folder type structure, staying away from the Arc geodatabases since we had both experienced problems with that type or organization.

The data that we are using for detecting the change in logging in the area is satellite imagery. More specifically it is TM data that has been georectified, the dates for the satellite images we are using are, 1985, 1995, 2000, and 2005. Pre processing included putting these satellite images into a common projection, NAD 1927 UTM 10N. The vector data that I acquired was all put into the same NAD 1927 UTM 10N projection as well.  The next step was to subset each of the satellite images to make them smaller, easier to work with, and faster to process.  Then we created a DNR park boundary layer file. This was laid over the top of each of the air photos to see where logging had occurred inside of the park boundary. Once all of this was accomplished we could then start comparing each image to each other.

The DEMs that were being used all needed to unzipped and placed in the proper folders to keep the data organized. For the viewshed analysis portion each DEM was already projected the same. Each DEM was used to create a hillshade which will then be used for the viewshed analysis. Right now we are at the stage where the various hillshades are not matched up properly and not displaying as a seamless display. The four separate hillshades will be mosaiced together but first the gaps and alignment issues must be taken care of.

Data flow diagram for change analysis

Data flow diagram for viewshed analysis