 ftp://edacftp.unm.edu/spenman/geog581L/examples_georefer ence FTP SITE

SHAWN L. PENMAN EARTH DATA ANALYSIS CENTER UNIVERSITY OF NEW MEXICO RASTER ANALYSIS PART 3

OTHER RASTER ANALYSIS TECHNIQUES

MERGE AND MOSAIC Mosaic to New Raster (Data Management) Mosaics multiple raster datasets into a new raster dataset Data cannot be in your mydocuments folder, has to be on regular drive

 Remove Noise, Majority Filter, etc. RASTER GENERALIZATION

CELL STATISTICS Calculates a per-cell statistic from multiple rasters. The available statistics are Majority, Maximum, Mean, Median, Minimum, Minority, Range, Standard Deviation, Sum, and Variety.

NEIGHBORHOOD STATISTICS Calculating neighborhood statistics is useful for obtaining a value for each cell based on a specified neighborhood. For example, when examining ecosystem stability, it might be useful to obtain the variety of species for each neighborhood to identify the locations that are lacking variability in the distribution of species.

COST WEIGHTED DISTANCE

SURFACE ANALYSIS

TERRAIN VISUALIZATION DEMs often look a little dull and un-natural, so we often use a hillshade grid theme (left) to apply as a brightness grid theme to an elevation gird theme to produce a more natural looking landscape (right).

VISIBILITY ANALYSIS

SURFACE INTERPOLATION

CUT/FILL FUNCTION

 Process of assigning spatial coordinates to data that is spatial in nature but has no geographic coordinate system.  Paper maps  Scanned aerial photos  Scanned maps  Maps from reports or publications that have data you want to use  Creates a spatially referenced image file that can be used as a background or you can digitize information into a new feature class.  Newly georeferenced image will have coordinate system and projection of reference data, although you may need to define it in ArcCatalog.  For example, if you are using an ESRI basemap as reference the projection will be WGS84 Web Mercator (auxillary sphere) GEOREFERENCING

1. Examine map are there any coordinates marked?  Are there landmarks?  Roads?  Coastlines? 2. Find a reference layer or basemap to use for georeferencing process  ESRI Basemap  Roads from a GIS Clearinghouse GEOREFERENCING

 Control points  locations that can be accurately identified on the raster dataset and in real-world coordinates.  road or stream intersections, the mouth of a stream, rock outcrops, the end of a jetty of land, the corner of an established field, street corners, or the intersection of two hedgerows.  Spread control points around image, try not to concentrate them in one area  Typically, having at least one link near each corner of the raster dataset and a few throughout the interior produces the best results. GEOREFERENCING

 Transformation  When you've created enough links, you can transform—or warp—the raster dataset to permanently match the map coordinates of the target data. You have the choice of using a polynomial, a spline, an adjust, or a projective transformation to determine the correct map coordinate location for each cell in the raster. GEOREFERENCING

 Root mean square error (RMS)  The error is the difference between where the from point ended up as opposed to the actual location that was specified—the to point position. The total error is computed by taking the root mean square (RMS) sum of all the residuals to compute the RMS error. This value describes how consistent the transformation is between the different control points (links). When the error is particularly large, you can remove and add control points to adjust the error. GEOREFERENCING referencing_a_raster_dataset/009t000000mn000000/

 We want to look at change in forest distribution over time. Has the distribution of species changed over the last 100 years? We have a map of Canada from 1906 with limit of forest trees indicated. We want to digitize those lines and compare with current data. EXAMPLE

  Texas A&M Map and GIS Library GEOREFERENCING VIDEO

ftp://edacftp.unm.edu/spenman/geog581L/examples_georeference FTP SITE

 New Mexico Land Classification 1882  Vegetation change over time  What reference can we use for this map? – Where in NM are we?  Geographic information?  Locations?  Physical features? 1.Add World_Latitude_and_Longitude_Grids.lpk to ArcMap  What is it’s projection? 2.Add NewMexico.jpg to ArcMap  Where does it end up? DEMO/PRACTICE Part?sort=Pub_List_No_InitialSort%2CPub_Date%2CPub_List_No%2CSeries_No&qvq=w4s:/when%2F1882;q:new%2Bmexico;sort:Pub_List_No_InitialSort%2CPub_Date%2CPub_List_No%2CSeri es_No;lc:RUMSEY~8~1&mi=11&trs=16#

4. Create Bookmark in general area of map 5. We need 4 points  106, 34  106, 35  108, 35  108, Start adding Control Points 7. After 4 points do we need to add more? 8. Rectify once you are finished to permanently transform your dataset. DEMO/PRACTICE NEW MEXICO

 London 1746 Map  How has the center of London changed over time?  What references can we use on this map? Is there any geographic information printed on this map? Is there anything different about the London map?  United Kingdom shapefile  Open Street Map Basemap MORE DEMO/PRACTICE