This week’s lab involves creating new data when you can’t get digital data. We’re going to digitize the relevant parts of the BV and Glasgow Geologic maps (by Dr. Edgar Spencer, Geology, Emeritus) and digitize the location of landslides that occurred in the map area in 1995 from color photos taken in 1998. To start: Copy the contents of the folder \geodatavol2GEOL260sharedworklabsdigitize to your lab2 folder Below is what you’ll input into the group project (all are depending on you, you’ll have to pull your weight on this). The map in the background is the seamed together topographic quadrangles for this exercise (‘bv&glasgow24kdrgs.jpg’) that will serve as the base for your new data. Georeferencing the jpg image (aligning the scan of the geology map to a projected or ‘geolocated’ drg (‘digital raster graphic’ or ‘image’) of the BV and Glasgow topo maps Now you will geolocate an aerial photograph 1998_NAPP_CIR_rotated.jpg from the digitize folder. Georeferencing is very hard to do in mountainous terrain without human features. What are you going to do about the spatial reference? (the projection?) Do not digitize from the ArcMap dataframe in which you did the geology map warping. As before, you must create a new dataframe and must set the projection information BEFORE you add layers. Either make a new file and bring in the data, or you can make a new dataframe, and copy the data into it.Use the same process as before, but this time you must make more ground control points throughout the photograph, particularly at the tops of hills and bottoms of valleys to get a proper rectification. Gather at least 15 or 20 points around the map, playing attention to the tops of ridges and valley bottoms. Use 2nd order or higher stretch to rectify the image. Don’t forget to save the rectification data points and note the RMSE (alt+PrintScreen). If you want to see how you are doing, you can compare the results to USDA image for Rockbridge County located in this folder \geodatavol2RockbridgeNAIP_2009_aerialortho_imagery. Note that this image is NOT in the same projection as what you have been using. Digitizing the slide data: At the head of the each slide, create a point. If you want some extra credit (+5 points), make a second layer, showing the downslope movement of the slides as polylines as far as you can follow them. The Polylines should have a node where they join (as you move down the stream), so you must either stop and restart a new line, or put a node where other slides join in. Make sure the snapping environment is working right for you. These layers should be put in your geodatabase. Here’s what the slide points and runout polylines look like near Davidson Run. Map as many slides starting points as you can identify. Sometimes the bottom of the landslide runout scar can look like the top, so check the topo map or a DEM if you have questions. When you’re done. Export your landslide feature class (the point file) and optional runout line feature class to this geodatabase Q:CoursesGEOL260landslides2015.gdb using this following name structure for slides_username slidelines_username To turn it in, drag a copy of the lab questionaire pdf to the ‘turnin’ folder on the L: drive, and send me an email telling me your web page is finished. Source.