Truckee Meadows slope-shade progress

7-21-2010_12-07-59_pm

I was able to create a gridded dataset from 2-ft contour data with some simple routines in GlobalMapper. Here is the first cut...note that it does contain some weird artifacts related to the irregular extent of the data. Now, we are working on carrying out the steps in ArcGIS. Having no success exporting the grid from GlobalMapper which is one of the only problems I have encountered with that otherwise excellent program. I suspect that I have to read the manual more thoroughly.

LiDAR-derived contours are useful, too.

9-29-2009_5-26-52_pm

Sure, I have gone on and on about the amazing visualizations you can get with some tweaking of LiDAR data; however, it turns out that a pretty basic representation is also quite useful...contours. Yes, contours. Sometimes smaller scale features remain somewhat ambiguous in hillshades or slopeshades, but high-res, short interval contours from the LiDAR data can eliminate most of the ambiguity. In this case, it is a tiny area that I have struggled with on the Owyhee River. Here, a large landslide entered from the north, shoved the river channel to the south, and the river eventually worked its way back to the north to some extent. The array of surficial deposits in the void that comprises the right hand side of the image south of the river record this sequence of events as well as subsequent sedimentation by tributary fans. The contours really highlight the fans, and in conjunction with discernible drainage patterns evident in the LiDAR, it is clear what is fan and what is river, right?

2-m Contours were generated in GlobalMapper and exported as shapefile to view in Arc. 

Note, Ian Madin (at DOGAMI) gave me the tip on contours especially as they relate to resolving fan features. He was right...it works!

Extent of lake caused by the Greeley Bar lava dam, Owyhee River, OR

9-29-2009_4-35-41_pm

I created this lake by generating a contour from the LiDAR dataset at an elevation of 1046 m. GlobalMapper does this in about 1.5 minutes. Then, exported the vector as a shapefile, cut out the parts of the line that occur downstream from the dam, stitch the remaining loose ends, build a poly from the line and there it is.

This lake has an interesting topographic correspondence with the old landslides on the south side of the Hole in the Ground as well as the ancient fan remnants that come in from the north side. Don't forget that much of the topography you can see through the lake didn't exist at the time of the lava dam. The valley floor was probably formed on the Bogus Rim lava which forms the flat-topped features that flank the left and right banks of the river near the eastern end of the lake. The top of the Bogus Rim lava is only about 25 m below the surface of this lake. Thus, the link between this lake and the landslides is dubious as there was nowhere for the landslides to slide.