help for Identifying true curves

[DorotheaKnigge]

Hello, 

We would like to identify dangerous tight curves in our road database.

To start I calculated a field called 'Sinuosity' with the following expression:

"!Shape.Length! / (math.sqrt(math.pow((float( !Shape.FirstPoint.X!) - float( !Shape.LastPoint.X!)), 2) + math.pow((float( !Shape.FirstPoint.Y!) - float( !Shape.LastPoint.Y!)), 2)))"

I then downloaded a geoprocessing script called 'Identify True Curves' which creates two output feature classes:

OutputCurvePoints and OutputWithCurves

It also creates two temp files: tmpSourceVertices and tmpDensifiedVertices

As the model runs, it gives me an error on both the OuputWithCurves and OutputCurvePoints . The error - 00117: Warning empty output generated. 

Am I missing something? I have made sure that the model paths are correct.

I am using ArcInfo 10.1.

I would much appreciate a work around or maybe even taking a different  approach.

Thank you,

Dorothea

[ChrisDonohue__GISP]

I don't know the specifics on the model mentioned but one possibility to bring up - it may be that the input data does not have the true curves it is looking for.  For example, if the input data was from a shapefile, none of the features in it would be a true curve, as shapefiles do not support true curves (shapefiles form a curve by using very short straight lines instead).  So getting a warning that an empty output was generated would technically be correct.

I'd run a test feature class that has a mix of true curves and densified curves to see how the model responds. 

Also, it may be that the model is set up to do something different than what you want.

Chris Donohue, GISP

[DorotheaKnigge]

Hi Chris,

I am using a file geodatabase not a shapefile.  Do file geodatabases support true curves?  I hadn't thought about that. 

[ChrisDonohue__GISP]

File geodatabases do support true curves.  However, of course, the depends on how the data got into the File Geodatabase.  If someone imports a shapefile into a File Geodatabase, it does not change the "curves" to true curves; they still remain many small straight lines.

Chris Donohue, GISP

[DorotheaKnigge]

Thank you Chris, 

I did import the data from a shapefile.  I will try exporting the data from our SDE geodatabase instead and see if that makes a difference.

[ChrisDonohue__GISP]

One caution, SDE supports several geometry types, but some of them do not support true curves.  We recently discovered this when we were considering moving to a different geometry type for some our feature classes in SDE for performance reasons.

Also, for other readers that are interested, I believe this is the model being used:

http://www.arcgis.com/home/item.html?id=267ce9c896a5480982cfa4bfa1747018 - Identify True Curves

Chris Donohue, GISP

[DorotheaKnigge]

That is helpful info, several years ago we moved the roads into an SDE binary format. Do you know if true curves are supported in the binary version?

[ChrisDonohue__GISP]

I don't know for sure on that one.  My SDE Administrator found that there were variations on the storage types not only based on what was specified but also what the Database is (in our case SQL Server), what version of database, and even in some cases what patches were applied.  It would probably take some digging to figure it out.

In regards to the issue you are trying to resolve, I wonder if there would be a way to take your data, irregardless of whether it is in a true curve or not, and process it to make true curves (like into a File Geodatabase).  Just pondering, but that would then allow running the model.

Also, let me tag a specific group.https://community.esri.com/community/transportation . They may know of a different approach to do the analysis.

Chris Donohue, GISP

[DorotheaKnigge · Accepted solution]

Chris, I have re-run the geoprocessing script using our SDE binary version of our Road Database (SQLServer).  It did not generate an empty output, so that is a good thing; but it didn't generate what I was hoping for either.  I will follow up with Transportation sector for a different approach.

Thank you for all your help and leading me through 'what makes a true curve'.  I learned some things today.

You must be getting a lot of rain in Roseville.  I am also in the Mother Lode:)

Dorothea