Latest Contributions by NeilAyres

‎04-09-2015

It is set up in the coordinate definition of the data. Once described properly, yes, you can leave your data "as is", and ArcMap can project it (or any other data) to whatever you want. What are the offsets? Start off with ArcCatalog, navigate to your mine data cad file, if there is no current spatial reference applied, go and select your NAD27 state plane, right click on it, 3rd option is to copy and modify. Give it a new name like "NAD27 State Plane NM - mine local grid" or something. Edit the X & Y shifts to the correct numbers. Viola. Put it in your favourites. If you use the normal file explorer, you will see that there is now a new prj file next to the CAD file (with the same base name).

‎04-08-2015

By "shift" do you mean an offset or truncation of X or Y axes or both? If you know what the offset is you can set up a "local" version of NAD27 stateplane NM west, with the X/YShift entered into the False_Easting / Northing values.

‎04-07-2015

I would look at the data first! Does it make sense? Does it (the WGS84 based data) overlay nicely with other RGF defined data? And, I thought the WKID / SRID was 1671.

‎04-07-2015

Can find no reference to that in the ArcGIS documentation. Just something called RD New and RD Old. So, is the DEM in metres (X, Y and Z). What is the EPSG code for "Amersfoort_Double_Stereographic projection"

‎04-07-2015

And, if they are "functionally equivalent", ie they overlay. Just redefine the WGS84 based data to be RGF. No transform is necessary anyway.

‎04-07-2015

Florian, that's the name of it. Arc ( and I would hope SDE) knows how to use them backwards and forwards.

‎04-07-2015

This "52.1 N Latitude" is not a coordinate system. Is the data in a projected coordinate system? This is recommended for this tool (and for most other analytical tools. If it is projected, then you don't have to specify a mid latitude for the data, because the system will already know that.

‎04-07-2015

That's a so called "composite" transform, a sort of 2 stage process. And this will work using the project tool. But sometimes, Arc makes some strange guesses as to correct composites. But as you want this to happen in Postgres... A quick check of the book (geographic_tansformations.pdf, in the documentation folder of the install), says there is a direct way to go from WGS84 to RGF_1993, it has WKID (I presume this is the same as a SRID) of 1671. But looking at the parameters for this, they are all 0 (zero). So RGF is already "functionally" equivalent. They are the same. So you may not have to do anything to your data, to get them to overlay properly.

‎04-07-2015

What is the coordinate system for your data? Is it in Holland....

‎03-31-2015

Sorry Brandon, but if you have saved it... If you are working in a SDE db, with versioning, you should be okay, the original data will still be there. If not, start looking for a backup copy.

‎03-30-2015

Darren is absolutely spot on. A field named Now (as a date) has the same result. Automatically populated... The only question is... Is this an undocumented feature or an undocumented bug.

‎03-30-2015

Darren, thanks for confirming this and for providing a possible explanation. Will try a "Now" attribute as well.

‎03-30-2015

This whole thing started when I wanted to make a random number column and populate it in an attribute table. I added a column to the table called "Rnd" (type double). Then I opened the field calculator to populate this with a random number. But then I noticed that it was already populated with a number, all the same. Even when I calculated the field to any number (in this case 2), a different random float would appear. Even opening the table would generate another. Strangely, after the calc above, I closed ArcMap, and opened the table in Access (this is in a personal geodb), the contents = 2. Is this behavior, for a field called "Rnd" documented anywhere? And, just in case I am totally loosing it, can someone confirm that this happens on another system. My version 10.2.2. Thanks.

‎03-26-2015

Copy and paster the original. Rename it. Open up the properties page in Catalog. Go to the Coord sys tab. Right click on the coordinate system. 3 option is to copy and modify. Give the your new coord sys a new name. Change the GCS at the bottom. Easy.

‎03-25-2015

This could, of course, be done using python / arcpy. It is a bit difficult to provide a ready made script without some more clues about the actual data. But the general flow might be : read the ID and NewXY into a python structure like a dictionary. Open up an Update cursor on the target, read each geometry, look up the new XY and update the existing. But another, non programmatic approach might be to use a topology between the 2 features. You existing stuff could be snapped automatically to the new points. Be aware that this changes the existing in place, so also make a copy beforehand before doing anything, just in case : Topology help : http://resources.arcgis.com/en/help/main/10.2/index.html#//006200000003000000

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My Ideas

Latest Contributions by NeilAyres

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Re: Local Coordinate Systems

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Coordinate Reference Systems