GPHY385, lectures 19&20
GPHY385, lectures 19&20 GPHY 384
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This 2 page Class Notes was uploaded by Sarah Massar on Saturday April 2, 2016. The Class Notes belongs to GPHY 384 at Montana State University taught by Stuart Challenger in Fall 2015. Since its upload, it has received 11 views. For similar materials see Advanced GIS and Spatial Analysis in Earth Sciences at Montana State University.
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Date Created: 04/02/16
GPHY384 Lecture 19&20 3/29&31 Lecture 19 3/29 SPATIAL DATA, UNCERTAINTY, AND ERROR -All data has some error -spatial -attributes -Sources of error -scale -date/lineage -compilation -Lineage/scale issues -ex. capturing roads from census blocks vs. GPS -TIGER- census geography -topology is the basis for census blocks -Digital Aerial Photography +Orthophotograph- imagery where distortion is camera lens/tilt and terrain have been removed -historic or archival imagery can be scanned into digital format +Photogrammetry- discipline that manipulates remote sensed data to get accurate imagry +GCDG- Geographic Coordination Database +FGDC- Federal Geographic Data Committee -a project to create spatial dataset of entire country in one communicated effort -leverages data development and cost -reduces duplication -accurate foundation +NSDI- National Spatial Data Infrastructure -a means to assemble geographic data nationwide to serve a variety of uses -asking locals for GIS information to make it accurate Lecture 20 3/31 RASTER- MAP ALGEBRA -for raster work, save as ArcRaster grid (tile looks like a waffle), not a geodatabase (tile looks like a gray cylinder) Map Algebra Functions 1. Local (per-cell)- intersects with only 1 cell location - Take exact same cell location from all the stacked layers - Nothing around the cell is taken into consideration - Ex. resampling, weighted overlay 2. Focal (neighborhood)- take cells touching target cell into consideration - Ex. slope - For slope, take the max difference between cells on either side to determine value of target cell - Default neighborhood is 3x3 +Block- neighborhood that is generalized so all cells become the same -start out different and then change to computed target cell value 3. Zone- all cells with the same value that can be contiguous or non-contiguous - Does calculation by zone +Region- a contiguous zone with the same values 4. Global- acts on whole raster -output is calculated using all the cells in the grid
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