Latest Contributions by MelitaKennedy

‎08-27-2015

No problem! Although I'm still trying to figure out what you're doing. Do you want Indian-based MGRS coordinates are features on this map? If so, you could try reprojecting the image (it'll be a copy) from WGS84 to the Indian datum. Open the Project Raster tool. Set the output coordinate system to...Indian 1975 UTM zone 48N (WKID 24048). The tool should want a transformation, use Indian_1975_To_WGS_1984_2. Melita

‎08-25-2015

I've seen similar problems posted before in the forums but haven't been able to find the threads. Summary of issue: features are not drawn in ArcMap, but if you select them in the attribute table (maybe also by drawing a selection box?), the selection graphics do draw. Mody, could there be a reference scale set on the layers? Ah, I was using a ill-formed search. Here's a similar issues: Features in Shapefile Don't Display in ArcMap But Exist in Attribute Table Melita

‎08-25-2015

I think I see. The image is georeferenced to Web Mercator which is based upon a spherical WGS84. You're not going to be able to match the MGRS/UTM values on the map because they're using a different datum. If I take 48QYD774226, unproject it to Indian 1975 latitude/longitude (16.47033139 107.59849798), transform it with 1304 (16.47191094 107.59431847), then convert it back to MGRS based on WGS84: 48QYD769229 That matches nicely with using the information button in the area of the boat ramp. I hope this is helpful, and makes sense. Melita

‎08-25-2015

And the enhancement/bug number is BUG-000090251.

‎08-25-2015

We (Esri-Redlands) are aware of the issue and are in discussions with Esri-China about possible solutions. The "eviltransform" solution on github is not accurate enough to match many of our online data. Besides, implementing a nonofficial solution like that would be illegal, wouldn't it? I'll add a comment with the bug/enhancement number once I have one (it has only an internal number currently). With that you can check its status.

‎08-21-2015

Have you set a geographic/datum transformation?

‎08-21-2015

What ArcGIS version are you using? Also check the filter to the left of the search box and make sure that it's not set. Melita

‎08-20-2015

You could use zone 55. Some transverse Mercator algorithms are only designed for 6-9 degrees from the central meridian, which you're hitting. The algorithm in ArcGIS can support your data's width. However, you're going to see bigger distance and area distortions outside the default zone width of 6 degrees. You could instead use Mercator (set the standard parallel to -7 or -8, or a conic projection like Lambert, but it would be a custom definition. Melita

‎08-19-2015

To expand a little, many projections that are designed to display the whole world like Mollweide, various Eckert ones, and so on do have sphere-only algorithms. Projections that support large and medium scale data (including all conformal projections) have ellipsoid and sphere algorithms.

‎08-19-2015

More than NAD27 used the 'old' (alternative) MGRS lettering schema. It is ellipsoid-based so Bessel 1841 was one of them, for instance. Although I would expect it to offset even more. If you try the Convert Coordinate Notation Tool, Input coordinate system would be GCS_Indian_1975 and output would GCS_WGS_1984. Input coordinate format would be MGRS and output coordinate format probably DD_2. Before you open the tool though, right-click ArcToolbox in the ArcToolbox window and open Environments. Open the Output Coordinates section. In the Geographic Transformations pull-down, select Indian_1975_to_WGS_1984_2 (you can start typing the name and it will scroll the list). OK Environments window, then open the Convert Coord Notation Tool. Melita

‎08-18-2015

Are you setting a transformation? The equivalent transformation In ArcMap to the one specified in the mapplet is Indian_1975_To_WGS_1984_2. We could also be having an issue between whether the "new" or "old" MGRS style is being used.

‎08-14-2015

The extent is probably being "reboxed". EPSG:102100 is Web Mercator which is a cylindrical projection. Latitude and longitude lines are perpendicular and square (parallel to grid north/south and grid east/west). EPSG:2913 is a US state plane zone for Oregon that uses Lambert conformal conic projection. Latitude and longitude lines are perpendicular, but not parallel to grid north/south and east/west lines. A rectangular extent in 102100 will be tilted slightly. If it's reboxed (find the min and max values), there will be new coordinate values. I took the original two values, found the other corners and then projected them: -13657052.8897704 5704031.99454925 -13654690.3533550 5705394.14433894 -13657052.8897704 5705394.14433894 -13654690.3533550 5704031.99454925 Unproject to lat/lon: -122.6833934690943 43.52171365960083 -121.6621704433817 45.53028630417766 -122.6833934690943 45.53028630417766 -121.6621704433817 43.52171365960083 Project to 2913: 7642556.797098541 683865.1900488964 7648078.003092581 686843.4524277482 7642641.258368226 686989.7029220903 7647994.362606527 683718.9174751663 You can see that the results in 2913 are no longer rectangular. While the first x (easting) value is the smallest, the smallest y (northing) value is the last one, not the first. Melita

‎08-13-2015

When you say that you've downloaded maps of Liberia, I have a feeling that you're downloading raster images of a map or otherwise "complete" map and not individual data layers that you can work with. You may need to look for shapefiles or a geodatabase with Liberia county or other administrative district polygons. If you can find some that already have attribute (census or other statistical data) attached, you're ahead of the game. I was able to find some possible data by searching Google for "liberia county shapefile" without the double quotes. Then you can choose to change how the polygons are symbolized. Add the shapefile or feature class to ArcMap. Right-click the layer in ArcMap and open its properties. Switch to the Symbology tab. In the left box choose to show by categories or quantities. If your statistical data is table-based, it will need to have a common field (like county name) so you can join it with the county polygon shapefile/feature class. Hopefully, this will help you get started. Melita

‎08-06-2015

I'm glad to hear that, Joe! This stuff isn't getting simpler, it's getting more complicated now that we have better solutions and datum re-adjustments.

‎08-05-2015

The Project Tool is giving a 'best' choice or a sorted list based on the data's extents and the transformation extents and accuracies. The geoprocessing environment list doesn't have access to your area of interest so just gives a list sorted by names. I usually try to define transformation in the same "order" that the source document uses. In this case, the WGS_1984_(ITRF00) one came from National Geodetic Survey CORS website. It's technically ITRF00 to NAD83 (CORS96 or HARN, more or less) and time-based, but we drop the time-based portion of the transformation. Depending on your version, you may have more recent ones like an ITRF2008 to NAD83 (2011). Melita

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Latest Contributions by MelitaKennedy

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