Latest Contributions by MelitaKennedy

‎03-09-2016

Caitlin, Can you post a sample coordinate pair from the original dataset (UTM)? If you add a basemap, does it look like it's overlaying correctly? Or if you change the data frame's display unit to decimal degrees, do they make sense? Generally, if the output of a Project shows up in a weird place, the original data will too. Melita

‎03-09-2016

I've been a student struggling with software and a new field...! gis.SE can be a bit of a scrum too.

‎03-09-2016

I also think it's Teale Albers. The question is whether it's the NAD27 or NAD83 version. The NAD27 version puts the data near the border of Sierra and Nevada counties. It would have to be a meter-based version too. The NAD83 feet version lands the data outside the state. That's assuming: easting / x = -33471.539 northing / y = 159239.375 Melita

‎03-09-2016

A few hints, although I don't do much analysis. 1. What coordinate system is the building dataset using? You'll want it to be in a projected coordinate system (PCS or ProjCRS), localized as much as possible for the city. You might be able to use http://www.epsg-registry.org to get some ideas (likely none available for the city, but the country might have several zones. Note: the ProjCRS will likely be using meters for the units which leads into question 2. 2. Do you have the square kilometer grid yet? If not see if QGIS has a "fishnet" or grid tool to make a polygon-based dataset. ArcGIS does: Create Fishnet. Make it in meters so that it matches the ProjCRS from (1). 3. Then you can intersect or do some statistical analysis--I'm not sure of the correct terms here. You may also have to think about whether buildings that in two or more "cells" of the grid should be counted. I hope this helps you to get started at least. Melita

‎03-08-2016

Bill, The point you gave is in State Plane California III. There are both US survey feet and meters version of this coordinate system, which uses Lambert conformal conic. Most map projections don't preserve distances, but using a coordinate system designed for a few counties should work pretty well. State Plane zones were generally designed to have distortion due to the projection of no worse than 1 part in 10000. Melita

‎03-04-2016

Rebecca Strauch, GISP Was it this blog post from Esri Australia? ArcGIS 10.1 Licensing in a restricted environment. | Esri Australia Technical Blog

‎03-01-2016

Yes, that's right, because we have no information on how the two ellipsoids (datums) are oriented relative to each other.

‎02-29-2016

I don't think they're the same. That is, there's definitely a World Geodetic System 1966 as well as Australian Geodetic Datum 1966. According to Wikipedia and ICSM, the ellipsoids are different too. I don't think I've ever seen any transformations for WGS66. Possibly just define a custom one, but leave the parameters set to zeroes. That will model the difference between the flattenings of the two ellipsoids (so latitude values will change) but that's it. Melita

‎02-26-2016

The coordinate system is unknown (or wrong), so you should use the Define Projection Tool instead to update the metadata. The Project tool should be used when creating a new feature class that's georeferenced to a new coordinate system from an existing feature class (that has a known coordinate system). Once you have the CRS defined, then use the Project tool to convert to the same coordinate system as your other datasets, if you want.

‎02-26-2016

Anything in lat/lon like EPSG:4269, a geographic coordinate system, is displayed using a pseudo-Plate Carree projection. That is the lat/lon values are treated as if they're already linear units and just displayed. That means there's a big east-west distortion because the poles are lines, not points. Melita

‎02-26-2016

I've asked a dev to create the list. It isn't in the doc (note to self: add enhancement request). I'll post the list here later today. UPDATE: File is attached. This is valid through 10.4.0. Structure is: object type: original WKID [authority] -> new/latest WKID [authority] Name You'll see changes EPSG-EPSG, Esri-EPSG, EPSG-Esri Example: pcs: 102100 [Esri:] -> 3857 [EPSG:] WGS_1984_Web_Mercator_Auxiliary_Sphere It also includes all objects types, including units, spheroids, etc. pcs: projected coordinate system vcs: vertical coordinate system gcs: geographic coordinate system gtf: geographic transformation dat: datum vdt: vertical datum lin: linear unit sph: spheroid vtf: vertical transformation Melita

Re: Official vs walkable hotels? · ‎02-24-2016

Six miles---hotel circle? Oh, I see, yes aka Mission Valley There's a decent trolley service that'll get you around some parts of San Diego. If it is hotel circle, you could use stop Fashion Valley stop. I don't know about shuttle service. I expect not (this is not an official Esri statement), and that you would be expected to take the trolley. Years and years ago, I stayed at La Pensione, a minimal hotel (starting around $150 during conference week) in Little Italy. It's walkable to the convention center or just a few stops on the trolley.

‎02-19-2016

This is an FYI (for your information) for others. The data had a non-Esri coordinate system definition in its prj file. One was that the projection name was "Lambert_conformal_conic_2SP" but we interpret that okay. There was also an "EXTENSION" keyword which contained the PROJ4 definition. We ignore that too. Something about that was messing up our reading of the AUTHORITY keyword, but that wouldn't/shouldn't affect interpretation of the rest of the definition. I'm most suspicious of the linear UNIT keyword which had the correct mathematical definition of a US survey foot, but the name differed and ArcGIS was treating it as a custom unit. Because the data was going to be used in a tiling scheme, there might be some hiccup there. I'm still looking into it. I suggested to Erik that if he wanted to try 10.4 again, to redefine the data with the Esri coordinate system. He reported that did clear up the offset he was seeing. Thanks for checking that, Erik!

‎02-18-2016

What I'm seeing is that the definition for Pierce county in the projection engine (a low-level library) shows 1 standard parallel, scale factor, and latitude of origin in the definition. In ArcMap, it's displaying 2 standard parallels (2 is equal to 1), so that shouldn't be causing a problem. That is, the definition without an explicit standard parallel 2 should be mathematically equivalent in the software to the one with an explicit standard parallel 2. Setting aside the tiling scheme, do the raster and vector layers overlay in ArcMap? If they're overlaying fine there, but not once tiled/published to a service, that changes the area of software that needs to be looked at. Any chance you could send me a small version of the vector data so I can test it here? If so, mkennedy at esri dot com. Or I have to recommend that you call technical support to get it officially into the system, and so that someone else who might call in can be linked to the same bug. Thanks, Melita

‎02-17-2016

Erik, Okay, I have a bunch of questions, which should help narrow down what's happening. Are you using WISCRS? Or the older county system? Which county? And does it use transverse Mercator or Lambert conformal conic? Can you determine whether it's the raster or the vector data that isn't working correctly? I suspect the raster. There was a lot of work down to our branch of GDAL (which handles raster coordinate systems). If you look at the coordinate system definitions of both data layers, are there any differences? Thanks, Melita

My Ideas

Latest Contributions by MelitaKennedy

Re: Custom Transformations

Re: How to start in GIS without previous knowledge and a defined problem?

Re: Strange California Coordinates (-21678.911, 157257.553) marked GPS_North, GPS_West

Re: How to start in GIS without previous knowledge and a defined problem?

Re: arcmap circle draw usage error?

Re: License Manager - Floating between different licence levels

Re: wgs66 transformation

Re: wgs66 transformation

Re: which Coordinate Reference System (CRS) and/or Projection?

Re: which Coordinate Reference System (CRS) and/or Projection?

Re: How can I find the WKID of coordinate system??

Re: Official vs walkable hotels?

Re: ArcGIS Desktop 10.4 Coordinate System Issues

Re: ArcGIS Desktop 10.4 Coordinate System Issues

Re: ArcGIS Desktop 10.4 Coordinate System Issues

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Re: New XY layer from Lat Long (DD) not plotting c...

Re: EPSG release and ArcGIS Projection Engine

Re: EPSG release and ArcGIS Projection Engine

Re: The vertical transformations WGS_1984_To_EGM96

Coordinate Reference Systems

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