TIN Tolerances

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06-22-2015 10:58 AM
DavidLamb
New Contributor III

Hello All,

I'm working on converting an AML script over to the latest version of ArcGIS. It uses TIN commands extensively to create TINS and Contours. I'm not familiar enough with the old TIN tool to find the equivalent setting sin 3D analyst.

For example, the tool sets the weed_tolerance and proximal_tolerance for the CREATETIN tool. These no longer seem to be available as parameters in 3D analyst.

I was thinking about thinning the points prior to using them in 3D analyst as a surrogate to proximal_tolerance, but it isn't clear what this tolerance actually does.  This is the only description I've found:

{proximal_tolerance} - tolerance used to ignore points, nodes and the remaining

weeded vertices that fall within the given distance. The default is the

machine precision of the computer. The {proximal_tolerance} is set to the

greater of two values, either the program-calculated value or the value you

enter.

weed_tolerance seems applicable only to polylines, and the Generalize tool might work for that.

The TINCONTOUR tool has a subdivision degree option that is used, but there doesn't seem to be an equivalent. I thought maybe something with a terrain pyramid might work...

Any thoughts?

Regards,
David

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DavidLamb
New Contributor III

In case anyone is interested, the workflow I discovered to duplicate the TIN Tolerance is:

Step 1 -> Only if you have multipoints. Assuming a field for the x and y coordinates, and a field for the elevation/depth.

Dissolve using the x and y coordinates. Calculate the statistic for the elevation field. The TIN appears to be based on the first value, but you could use MIN, MAX, MEAN or LAST.

Step 2

Sort the data based on the SHAPE filed, Ascending, and LL.

Step 3

Delete Identical, set the XY tolerance to the same as the Proximal Tolerance. For larger values, it does seem to be the Proximal Tolerance - 1 to exactly duplicate.

Step 4

Use the last feature class to create the TIN.

I haven't found a method to duplicate the subdivision process when generating contours.

Regards,
David

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DavidLamb
New Contributor III

In case anyone is interested, the workflow I discovered to duplicate the TIN Tolerance is:

Step 1 -> Only if you have multipoints. Assuming a field for the x and y coordinates, and a field for the elevation/depth.

Dissolve using the x and y coordinates. Calculate the statistic for the elevation field. The TIN appears to be based on the first value, but you could use MIN, MAX, MEAN or LAST.

Step 2

Sort the data based on the SHAPE filed, Ascending, and LL.

Step 3

Delete Identical, set the XY tolerance to the same as the Proximal Tolerance. For larger values, it does seem to be the Proximal Tolerance - 1 to exactly duplicate.

Step 4

Use the last feature class to create the TIN.

I haven't found a method to duplicate the subdivision process when generating contours.

Regards,
David