This workshop walks through the process of generating maps from Total Station data in Arcmap. It is developed on ArcGIS 10.0 (sp4) and therefore tools and procedures may be different in other versions. The basic procedure involves saving the SDR file generated by SokkiaLink into a Point shapefile, then using the Points to Line and the Feature to Polygon tools in ArcToolbox Data Management Tools to convert these points into polygons. Finally we generate a map using these data. In making viewshed calculations, the earth's curve and the refraction of light in air have an impact (albeit minor) on lines of sight. I this post, I provide some links describing how Arc calculates both variables. I would love to find out how to recalculate the 'refractivity coefficient' of 0.13 to other situations. I also put a plug in for fuzzy viewsheds, a drastic improvement that was first suggested 15 years ago, to be mostly ignored in practice until very recently. Before you can start the process, you have to choose from the many transformations. The attached file (World Projections.xls) lists where in the world each projection transformation should be used. For example, if your map is in PSAD56, and you want to project it to WGS84, the Project Tool will ask you which transformation you want. Checking the lists for Bolivia, I find: PSAD_1956_To_WGS_1984_2 Before you can start the process, you have to choose from the many transformations. The attached file (World Projections.xls) lists where in the world each projection transformation should be used. For example, if your map is in PSAD56, and you want to project it to WGS84, the Project Tool will ask you which transformation you want. Checking the lists for Bolivia, I find: PSAD_1956_To_WGS_1984_2 Experimenting with raster compression formats with a scan of a ~D sized paper map (300 dpi) I found that after georeferencing (using Lat/Long) I could create a 18mb JPG file together with its JGW worldfile at about 80% JPG compression. How large would this file be in a non-lossy format that is widely readable by non-GIS users? The matrix of cells that appear in the Batch command can be difficult to fill-in, however I've found that you can construct a more elaborate batch in MS Excel and then paste those values back in to the ArcGIS batch window. ArcGIS offers a number of geographic transformations between coordinates in the older Prov South American Datum of 1956 (PSAD56) and the modern WGS 1984 datum. The PSAD1956 datum is supported in ArcGIS. The coordinate system settings are found under Coordinate System menus under UTM (Universal Transverse Mercator) Summary: This technique allows a user to bring scanned maps and other rasters from a variety of projections and coordinate systems into a common reference system. The idea is that a vector file can be transformed more easily than a raster file, so a vector border of a raster map is transformed (in lieu of the raster itself), and then the raster is re-georeferenced to the new vector position. Source.


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Last Modified: April 22, 2016 @ 6:03 pm