Latest Contributions by MelitaKennedy

Hi Matt,  We've been debating how to implement time-based transformations which would include the ability to persist epoch (date-of-collection) information as well. The ISO metadata standard has now been updated so that information can be stored there. That still can cause some issues in the projection engine because that library sits so low in the software stack that we would have to figure out how to access the metadata files!    We've been adding the transformations and some supporting functionality to the projection engine but we still need to get it exposed above in the software stack.  Melita ... View more

Hi Aaron,  Your post may be moved to the coordinate reference systems 'place' as this one is for the Runtime SDK for Java rather than the Java Geometry API.  You're correct that you'll need to project the geometries to a projected coordinate reference system before buffering. I wouldn't suggest using 3857 (Web Mercator) as it's quite distorted except near the equator. There's not a good answer for you. Even for so-called 'equidistant' projections, they maintain distances from one or two points or along certain lines, like all north-south lines.  One intensive solution is to create a custom projected coordinate system for each geometry. If they're points, center an azimuthal equidistant projection, run the buffer, then reproject to whatever coordinate reference system you're using. If you don't need really accurate results and are instead okay with 1 part in 2500 accuracy at the worst AND working within 3 degrees of longitude, the local UTM zone would be okay. A shortcut for UTM zones are that the WGS 84 ones have well-known IDs that look like: 326 + zone number where zone number is 01 - 60 for the northern hemisphere and  327 + zone number for the southern hemisphere I'm not going to replicate the pseudo-code here, but there's a post on GIS stackexchange that shows how to calculate the UTM zone from a latitude-longitude point. Melita ... View more

Sorry, not yet!! My team hopes to concentrate on geoid models/vertical transformation grids in the next release. ... View more

You still need to convert between latitude-longitude and XYZ. See section 4.1.1 of IOGP / EPSG Guidance Note 7-2. It's available from https://www.epsg.org.  ... View more

Hi Xander,  Yes! And they need converted to XYZ. There is an abridged Molodensky method that uses decimal degrees directly--but accuracy is a little less. After converted through the conformal 3D equation, the output XYZ need to be converted back to lat-lnng-ellipsoid h. That conversion is usually iterative but I think there are some direct but less accurate conversions. Melita ... View more

Duh! mkennedy at esri dot com ... View more

Hi Lauren,  I'm very sorry for the late response. Can you post the equation/steps the surveyor gave you for the data? For CAD data it's sometimes possible to assign translation/rotation/scale values to a CAD layer. It's also sometimes possible to modify the projection parameters (scale factor, false easting, false northing) and create a custom coordinate system that gets the data to match up. I have two documents that discuss some of this. If you (or anyone else) sends me an email, I'll send them. They're pretty old now and written for ArcGIS Desktop so workflows may be different if you're using ArcGIS Pro. Melita ... View more

Are you converting the input coordinates to radians and converting to XYZ? The main equations look okay to me. ... View more

We don't support 3D Cartesian in ArcGIS yet. It is in the Esri projection engine, but not exposed in the software using the library. I'm sorry! Melita ... View more

I don't think it's actually MGRS. MGRS is an alphanumeric system for locations. By default, it's only accurate to the nearest meter (+/-0.5, actually a little more) although we support MGRS strings up to mm precision. It might be UTM, which MGRS is based on. ... View more

Hi everybody,  I'm sorry that I didn't respond to this before. Both ArcMap and ArcGIS Pro support on-the-fly reprojection which often includes a geographic/datum transformation component. Both software packages use the same underlaying code, so if you have different results, it's usually because they're not using the same transformation. Open the map or data frame properties and make sure the same geographic transformation is being used.  ArcGIS Pro will often automatically select a transformation, but ArcMap doesn't do that, so it's easy to have the two giving different results. Melita ... View more

Hi Erik, I'm sorry for the delay in responding. There has been no update in the release of files/test data from NGS. However, NGS has said that they are going to delay the adoption of NSRS / 2022 for a few years. See Delayed Release of Modernized NSRS | New Datums | National Geodetic Survey  and Track Our Progress - New Datums - National Geodetic Survey . The summary is that the official adoption will likely occur in 2025, although they'll keep the 2022 name. Meanwhile, we implemented for ArcGIS 10.8.1 and ArcGIS Pro 2 a variant of Lambert conformal conic projection that will be used by NGS for the new state plane and other zones. It was already supported but awkward to use. We're still following NGS closely. Melita ... View more

Thanks, Justin. I just wanted to be sure! I have the files, but am swamped right now. I'll get to them soon. Melita ... View more

Hi Robert!  I don't see the attachment--maybe post a link? Is it the table of different map projections and their properties or the pdf file that lists projected coordinate systems, areas of use, etc? If it's the pdf file, look in the geographic coordinate systems pdf. That contains the vcs info too. Melita ... View more