Latest Contributions by MelitaKennedy

‎10-18-2017

In the Insert map box, select Computer in the left browse window. Then try typing the folder path in the search box: \\esripress\gtkarcgispro. Or on the Insert tab, select Add Folder. That will let you add a folder connection. Melita

‎10-11-2017

This method would still mean creating separate datafiles for each region. A possible way to do this is to modify the coordinate systems for each region if they're using a projected coordinate system. You could adjust the false easting and/or the false northing parameter values to "move" the data from its normal location. You would use the Define Projection tool, or the data's property page, NOT the Project tool. Melita

‎10-09-2017

Could you hear me screaming? I follow a surveyor's forum, mostly US people, and there's definitely people who have problems with "GIS". Admittedly, the GIS department in question is often using scanned tax maps to show parcel boundaries...

‎10-04-2017

Once you start using ellipsoids rather than spheres, it's much more difficult to directly use a developable surface. It is a good approximation, particularly for understanding in general how projections work. Think about projections like the Eckerts. I call them cylindrical but they're actually pseudocylindrical. Eckert IV and VI have poles-as-lines that are a percentage of the equator so right there they're not truly cylindrical. Adjustments like that are the rule rather than exception for most projections because otherwise you have very simple projections that really don't do much. Melita

‎10-04-2017

Hi Chuck, Most projections will not "stitch together" on the edges. Polyconic is one that will, normal cylindricals (not transverse or oblique Mercator) as well. A state plane zone is designed for the zone's area, not whether it will match up with neighboring zones. I hadn't heard that state plane zones were designed for continuity for large areas (except within a zone). Instead, I think it was to define a coordinate reference system with overall linear distortion no worse than one part in 10000. Melita

‎09-20-2017

Vector data now support some vertical transformations starting with ArcGIS Desktop 10.4.1 and ArcGIS Pro 1.4 (Project tool, on-the-fly in Pro 2.1) although your use case is only indirectly supported (I know, I know!). Anyway, raster support for transformations is coming later, possibly in 10.6 / Pro 2.1. Your workflow should work, apply the scaling then redefine the vertical coordinate system. Melita

‎09-19-2017

My suspicion is that your data is not within the published area of use of the Nahrwan 1967 geographic coordinate system. Here's the extent information that we're using: 1351 "Asia - Middle East - Qatar offshore and UAE" \ min latitude: 22.63 max latitude: 27.05 min longitude: 50.55 max longitude: 57.13 Nahrwan 1934 has different extents. 3390 "Asia - Middle East -SE Iraq and SW Iran" \ min latitude: 29.06 max latitude: 33.5 min longitude: 44.3 max longitude: 51.06 I just took a quick look at the transformations we have. Nahrwan 1967 to WGS 1984 (2) is listed for Saudi Arabia - onshore Arabian Gulf area. That area of use has only a slight overlap with the 1351 above. Try adding some "world" data to the map. Can you please let me know (via email if you want, mkennedy at esri) where the data is located? I'm trying to share the information with the EPSG geodetic parameter registry subcommitee to get the areas of use updated. (I'm on the subcommittee) Melita

‎09-14-2017

My team is looking for a new member. Here's the job posting Feel free to contact me for more details or questions, but all resumes must go through the usual submission process (via the Careers website). OVERVIEW Do you think map projections are cool? Know what a datum is? As a projection engine product engineer, you will help build and support functionality that affects every ArcGIS user. Our team is responsible for handling projected and geographic coordinate system transformations and all issues that pertain to coordinate systems and measurement interactions within our software applications. Come and join us at the base of the software stack working on the Esri projection engine. RESPONSIBILITIES Design and develop test plans and test cases, write test code, and execute and analyze tests to support and enhance overall product quality Research and analyze customer requests, industry standards, and specifications to help define requirements Showcase new capabilities to customers and colleagues via user documentation, blog posts, and resource center content Help define and refine future capabilities of the software REQUIREMENTS Working knowledge of a programming language such as C, Java, Python, or similar Be detailed-oriented and a self-starter Excellent written and verbal communication skills Bachelor’s or master’s in GIS, computer science, math, geodesy, geography, or a related field Recommended Qualifications: Minimum of six months working with ArcGIS products Working knowledge of GNSS and geodesy Mathematically inclined

‎09-14-2017

That's correct about the input data. The cell size is always in the same units as the coordinate system, so they're in degrees.

‎09-13-2017

That extent is smack in the middle of zones 10 and 11. UTM uses transverse Mercator which maintains shapes (angles), not areas nor distances. It's impossible to maintain all distances. Normally you get all distances from the center point, or along all longitude lines plus any standard parallels. Depending on which version you have, there are tools or arcpy functions which can return "geodetic"-based areas and distances. Here's a link to a blog post discussing the calculation of the geodesic-based areas in the field calculator. If you want the data stored in a equal area projection, you could design your own. Albers is a conic projection or cylindrical equal area would work. If you want to stick with transverse Mercator, I would do a custom one with the central meridian at -117. If you leave the scale factor at 1.0, the central meridian will have no distortion. Otherwise, adding a scale factor, like 0.9996, will move the no-distortion lines out away from the central meridian. UTM zones were designed to be no worse than 1:2500 (which occurs along the central meridian and the zone edges). Melita

‎09-13-2017

The output cell sizes are really, really small for projected data. What happens if you make them more appropriate?

‎09-08-2017

The gdaldata folder files are used by raster only to support coordinate systems in rasters. They are not otherwise used.

‎08-31-2017

The json file already lists transformations whether the data is there or not. It's more likely that the particular path you need isn't in the file. It's missing quite a bit of cases. If you can post (or email me, mkennedy at esri) the source and target coordinate systems, I can check the json file for you. Melita

‎08-23-2017

If you're willing to use ArcObjects check out IConversionNotation or IConversionMGRS.

‎08-22-2017

If you're checking the transformation in ArcMap, make sure you've selected the correct "from"/source GCS in the top box. That will change the list in the Using pull-down and show what's set for each unique from/to pair of GCS.

My Ideas

Latest Contributions by MelitaKennedy

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Re: The vertical transformations WGS_1984_To_EGM96

Re: The vertical transformations WGS_1984_To_EGM96

Coordinate Reference Systems

Alaska GIS Users