Latest Contributions by MelitaKennedy

Brianna, I'm checking on it. As far as I'm aware, the Define Projection tool and a raster's property page do have VCS implemented yet. I just tried a 10.4.1 beta and don't see how to add a VCS to a raster. Joseph, again, as far as I'm aware, rasters are not explicitly supporting vertical transformations yet. We just added that functionality for vector data to the Project Tool in ArcGIS for Desktop 10.4.0. Melita ... View more

Did the height value change at all? I do not work with rasters very often. I think you may need to put one into the other's coordinate system, including applying the geographic/datum transformation, GGRS_1987_To_WGS_1984_1. Even if the software is converting one raster to the other coordinate system internally (on-the-fly) before doing the calculation, the datum transformation may not be done, which would throw off the results. Melita ... View more

No, they are different transformations. Here are the values: PE_GT_WGS_1984_ITRF08_TO_NAD_1983_2011 \    "WGS_1984_(ITRF08)_To_NAD_1983_2011" \    PE_GCS_WGS_1984 \    PE_GCS_NAD_1983_2011 \    PE_MTH_COORDINATE_FRAME \    PE_PAR_X_AXIS_TRANSLATION:+0.99343 \    PE_PAR_Y_AXIS_TRANSLATION:-1.90331 \    PE_PAR_Z_AXIS_TRANSLATION:-0.52655 \    PE_PAR_X_AXIS_ROTATION:+0.02591467 \    PE_PAR_Y_AXIS_ROTATION:+0.00942645 \    PE_PAR_Z_AXIS_ROTATION:+0.01159935 \    PE_PAR_SCALE_DIFFERENCE:+0.00171504 PE_GT_WGS_1984_ITRF00_TO_NAD_1983_2011 \    "WGS_1984_(ITRF00)_To_NAD_1983_2011" \    PE_GCS_WGS_1984 \    PE_GCS_NAD_1983_2011 \    PE_MTH_COORDINATE_FRAME \    PE_PAR_X_AXIS_TRANSLATION:+0.9956 \    PE_PAR_Y_AXIS_TRANSLATION:-1.9013 \    PE_PAR_Z_AXIS_TRANSLATION:-0.5215 \    PE_PAR_X_AXIS_ROTATION:+0.025915 \    PE_PAR_Y_AXIS_ROTATION:+0.009426 \    PE_PAR_Z_AXIS_ROTATION:+0.011599 \    PE_PAR_SCALE_DIFFERENCE:+0.00062 The transformations occur in 3D Cartesian space, and you can see the differences between the two are pretty small. ... View more

The Trimble rep may have been talking about NAD2022 and NAVD2022. NGS is planning on replacing NAD83 and NAVD88 around 2022. From what I understand, they'll be 'dynamic datums' and update as needed rather than have a static re-adjustment every few years. It depends on what you're planning to do with the data. If you're merging it into a database that's using an older WGS84/ITRF or NAD83 realization, then you might want to transform it to match the database. ... View more

The function that puts together the list of suggested geographic/datum transformations is easy to fool. It's looking at extents and accuracies and adding a world base map can throw off its suggestions quite a bit. When I include ITRFxx in parentheses in a geographic transformation name, it's specifying which realization of WGS84 it should be used with. It's not actually a part of the transformation definition so the projection engine library is not taking (ITRFxx) into account. I also add "duplicates" of an original transformation but for other, related realizations or re-adjustments like NAD83 (CORS96) and HARN which assume the related realizations can be considered equivalent based on the data accuracy. I also sometimes added "NAD 1983" equivalents for some of the older, ITRF00 transformations assuming that people had data defined as "NAD 1983" but that it was more likely a later re-adjustment. I haven't done that for ITRF08. Now there's also GEOCON and GEOCON11 transformations to move between HARN/NSRS2007/2011/others. We have GEOCON/GEOCON11 v1 in 10.4.0, but not the beta v2 which adds yet more re-adjustments on a state-by-state basis. Thank you for pointing that there are errors in the knowledge base article, 24159, the extent for WGS_1984_(ITRF08)_To_NAD_1983_2011 should be North America, with the next two, Pacific Ocean (Pacific plate), and Marianas Plate. I ended up talking to the article owner while I was writing this reply and she's opened a draft of it so I can fix it (the current version will remain on the website until it's fixed). Melita ... View more

Okay, thanks to Kofi Lartey, I got the e00 files. One, a country boundary file with at least level 1 administrative districts, is in a custom projected coordinate system, complete with a custom ellipsoid. Projection    TRANSVERSE Datum USER_DEFINED 0.000 0.000 0.000 0.0000 0.0000 0.0000 0.0000 Zunits        NO Units         FEET Xshift        0.0000000000 Yshift        0.0000000000 Parameters 6378295.0000000000  6356746.0000000000 0.99975000 /* scale factor at central meridian -1  0  0.000 /* longitude of central meridian 4 40  0.000 /* latitude of origin 274320.00000 /* false easting (meters) 0.00000 /* false northing (meters) The projection parameters are the Ghana National Grid / Metric Grid (although the false easting differs by about 0.5 meter). The custom ellipsoid has a flattening around 1/295.9903. The custom ellipsoid is close the "War Office" so there may be a Gold Coast foot/metre conversion issue. Anyway, the other two coverages are definitely converted from rasters. Here's a close-up: Also complicating the issue is that these two files don't share the same country boundary. There could be a datum difference between them, but the offsets are not regular, so it's hard to say for certain. ... View more

I had to go track down an ArcInfo workstation book to look up the "Units 0.001" definition. A custom unit's value is defined as units per metre. So that stands for kilometres, not millimetres. Even with that information, the coordinate extents still don't make sense unless the data covers Ghana plus a bunch of countries to the north and east. If I very roughly check Ghana's extents against the 2455x3576 "cell sizes", I get around 5 meters per "cell". That's not too bad for a raster that might have represented soil or rainfall data. I don't know if you're willing to send one of the files (shapefile, .e00, whatever) to me (mkennedy at esri dot com) so I can look at it. Melita ... View more

Hi Kofi, That message occurs when either the input or output geographic coordinate systems don't match the internal definitions. So the software sees them as "different" so thinks that there should be a geographic/datum transformation OR there's no transformations available between two "known" GCS. A workaround if the input/output GCS are supposed to be the same is to add the data to ArcMap and set the data frame to the coordinate system you want to convert to. Ignore any geographic/datum transformation warning message. Right-click the data layer in the table of contents and choose data, export data. In the dialog, set it to use the data frame's coordinate system and export the data. Melita ... View more

They may overlay each other because they cover the same area, but are in "raw" meter-based values. The numbers don't make sense for either Ghana grid (Accra or Leigon GCS/datums) that's in ArcGIS. Both should have all positive easting values. If they are in meters, should the data extent be 2.5 km by 3.5 km? What location / approximate area should these datasets represent? Melita ... View more

Could this data have come from a converted raster? The -0.5 value is classic for a raster that hasn't been georeferenced. What coordinate systems are within 60 meters? ... View more

You can search by name or area in ArcMap data frame properties, coordinate system tab. There's also a PDF file in the documentation folder of the ArcGIS for Desktop installation which lists areas of use. Much of this information comes from the EPSG Geodetic Parameter Registry--which is where Georepository, spatialreferences.org, epsg.io also got their information. Melita Disclosure: I'm on the subcommittee that maintains the EPSG Geodetic Parameter Registry. ... View more

In addition to the "New" status, I'm not seeing any sign that it was migrated to the Development bug tracking system. Contact your sales rep/distributor/technical support to ask about it. ... View more

Unfortunately, you're not going to get negative coordinates using a state plane zone, unless the data is well outside the zone's defined area of use. The state plane zones (and UTM) were designed when doing calculations by hand or maybe on a desktop calculator. You didn't want to have to deal with both positive and negative values. Melita ... View more