topic Re: needing a little help with a gdb and a standalone table in Data Management Questions

needing a little help with a gdb and a standalone table

MikeHenson — Mon, 26 Jan 2015 20:53:06 GMT

I was given a gdb from a client containing a water system (lines, valves, meters, etc). Not a large one. I subsequently asked if there was any elevation data obtained when the data was field surveyed. He then sent me a standalone table titled "gpsPositions" Could have have someone look at these and tell me how to "join" them? Any help would be greatly appreciated.

MKH

Re: needing a little help with a gdb and a standalone table

JoeBorgione — Mon, 26 Jan 2015 20:57:41 GMT

Were you meaning to have someone on the forum take a look at your data? If so it didn't make the post.

If they did it right, there should be a common id between the two. If not, you're going to have to figure it out on your own.

Re: needing a little help with a gdb and a standalone table

MikeHenson — Mon, 26 Jan 2015 21:05:28 GMT

would add the data, but can't find the place to add an attachment

Re: needing a little help with a gdb and a standalone table

MikeHenson — Mon, 26 Jan 2015 21:10:01 GMT

found it.... see attachment

Re: needing a little help with a gdb and a standalone table

JoeBorgione — Mon, 26 Jan 2015 21:23:40 GMT

You might try creating a feature class of the gps points using add xy data. Then you could make an assessment as to which gps data is associated with the each of the features. Or you could add two new columns in your point data and use the geometry calculator to add in the value for x,y and compare them.

I'm kind of scratching my head though as to why you need the gps data at all; you already have points...

Re: needing a little help with a gdb and a standalone table

MikeHenson — Mon, 26 Jan 2015 21:32:21 GMT

don't need x, and y....because as you mentioned I already have locations. We need elevation data to model the water system. SOftware uses elev to determine needed pressures, etc.

Re: needing a little help with a gdb and a standalone table

MikeHenson — Mon, 26 Jan 2015 22:24:32 GMT

being new at this....do you see any way I can join the gdb to have the elevations?

Re: needing a little help with a gdb and a standalone table

JoeBorgione — Tue, 27 Jan 2015 02:47:28 GMT

As mentioned, add the gps data as an xy event layer and save it to a feature class. You could then perform a spatial join between your new set of points and each of your existing poit feature classes.

Re: needing a little help with a gdb and a standalone table

XanderBakker — Tue, 27 Jan 2015 02:53:00 GMT

For the point featureclasses you can use the Spatial Join to join the elevation from the closest GPS point to the features. There are a lot of GPS points around the features, but the spatial join will only pass the data of the nearest feature. In this case I didn't much variation in the elevation, so that will probably not be an issue.

Add the table to the TOC, right click on the table and select Display XY data:

For the feature layer that is added enter the properties, activate the Fields tab and switch off all the fields that aren't relevant (this will avoid them to be joined to your features):

Just leave the one with the elevation switched on (I assume it is ProjectedZ). Next right click on the featureclasses you want to enrich with the elevation, and select Join and Relates..., and Join. Select Join data from another layer based on spatial location, select the XY events (GPS data), select each point will be given all the attributes..., specify the output and click OK.

A new featureclass will be created with the elevation added and a field with the distance between the features and the GPS point from which the elevation was joined.

For points this is easy, for lines you cannot do this. The GPS points are also to sparse to interpolate the elevation and create a surface (TIN). Although you could try and use that to convert the lines into 3D lines. Another possibility would be to interpolate the elevations between nodes with a GPS point close, but that would require some programming.

Re: needing a little help with a gdb and a standalone table

XanderBakker — Tue, 27 Jan 2015 02:54:55 GMT

Here a fgdb with the joined points (they are now outside the feature dataset, and the lines are not included).

Re: needing a little help with a gdb and a standalone table

MikeHenson — Tue, 27 Jan 2015 14:35:03 GMT

Xander...that is really great. I'm going to continue this thread with an issue on this data. I have changed my coord system to arkansas north state plane, and when i list the location, I am still getting what looks like meters. Do i have to convert those to feet? I was assuming when I change my coord system, that it would adjust elevations too. Any info on this will be greatly appreciated.

Mike

Re: needing a little help with a gdb and a standalone table

XanderBakker — Tue, 27 Jan 2015 16:47:06 GMT

Normally I would suggest that you "close" this thread and start another. You can do this by marking the post that answered you question as the correct answer. In the other thread if necessary you could include a link to this thread. The description of this thread may not attract the correct audience.

First of all when you change a coordinate system you normally project the data to another coordinate system. This is the process of changing the coordinates of the geometry by the projection and possibly a transformation. A coordinate system can have a vertical reference in meters or feet or any other unit.

When projecting, the XYZ values of the geometry change, the values in the attribute table do not change.

I am sure that Melita Kennedy who is really an expert in this field can provide you with a more adequate answer.