TINS

A TIN or Triangulated Irregular Network is the final result of processing a scan or cloud and are the basis upon which most data extraction is performed. The TIN structure itself is a set of vertices and a set of edges and faces that connect those vertices as well as any color or intensity values that were in the cloud or scan that the TIN was created from.

Importing a TIN

One can import a .tin file simply by right-clicking the TINes folder and selecting Import and navigating to the .tin on disk.

Creating a TIN

There are several methods for creating a TIN, but all of these methods use one of two cloud creation dialogs. The most common and direct method of creating a TIN is to right click the source data object (either another TIN, a cloud or a scan) and select Create ⇒ TIN. You can also access the Create TIN dialog form the Action Tab. Creating a TIN from another TIN will re-triangulate the points in that TIN based on the new normal information provided in the Create TIN dialog, so it is entirely possibly that your new TIN can look completely different.

This dialog operates in two different modes: multiple source mode and single source mode. The single source mode is typically the result of right-clicking a data object in the PointCloud tree structure and selecting Create TIN or from the Action Tab, this mode only allows the TIN to use the originally selected data as its source. Use filters determines whether or not to filter out vertices based on any filters applied to the source object. The Normal is the direction to use for the Delaunay TIN triangulation; typically you want to use an axis that is representative of the direction that the data was taken from, such as the view direction of the scanner. In the case of scans, there will be a From Scan radio button that you can use, which will automatically use the scanner position information from the scan as the normal. The TIN Faces panel allows you to set restrictions on the TINing process. No edge in the TIN will be created if it will exceed the Maximum edge length or if the angle between the two faces it connects exceeds the Maximum incident angle. TIN Vertex Limits specify the maximum number of TIN vertices that will be used in a TIN. Setting this value too low may result in no TIN being created. One can also create a TIN with multiple sources by right-clicking the TINes folder and selecting Add ⇒ New, this will bring up a dialog similar to the one above with an extra tree control to the left.

All of the controls on the right half of the dialog are the same, but you can now toggle inclusion of objects into the TIN by clicking the red x next to their name in the tree, turning the icon to a green circle.

Smooth TIN

The Smooth TIN command allow you to create a new TIN or modify the existing TIN. There are two methods for smoothing. They may be used separately or in combination.

Smooth Spikes applies the user values for the parameters to remove or reduce the number and severity of spikes in the selected TIN.
Average

TIN Simplification

Simplifying a TIN is one of the key ways to reduce data down to a state that it can be transferred over to CAD software or to make it more manageable in PointCloud without losing much surface quality. Right-click the TIN to simplify and select Simplify. This will open the Simplify TIN dialog.

There are two methods of TIN simplification available. The Elevation Difference method will loop over all the vertices in the TIN Passes number of times and each vertex whose deletion would lead to a deviation in the TIN of less than the Threshold will be deleted. Elevation Difference is generally slower. The Edge Cost method determines the total deviation in the TIN that result from each edge removal (by merging its two vertices) and removes all edges whose removal would result in a deviation of less than the Threshold. In addition, the preserve breaklines options for the Edge Cost method will multiply the deviation value calculated by the Breakline Weight if the angle between the two faces it borders is greater than the Breakline Angle, this can be used to help preserve corners. The Elevation Difference method is best used in largely flat data (such as a scan of a large open area), while the Edge Cost method is best for complex data with lots of corners. Additionally there is a memory tradeoff, the Elevation Difference method is generally slower at higher numbers of passes (which gives better results), while the Edge Cost method consumes more memory.

Cleaning a TIN

To remove spikes from a TIN, right-click the target TIN and select Clean.

Vertices that meet the parameters of this dialog will have their positions adjusted to meet the shape of the vertices around them, smoothing out the TIN. These parameters are as follows:

Search Distance determines the distance for a vertex to search for vertices that exceed the Delta % Slope.
Delta % Slope is the maximum change is slope that is allowed. Vertices that exceed this value are removed.
Passes determines the number of passes to make over the TIN.

Resample a TIN

Resampling a TIN goes through the list of points in a TIN and takes one out of each "Step Value" points.  Therefore the number of points in the resulting TIN will be (1 / Step Size) times the original number of points in the TIN.

To run this command, right-click on the existing TIN and select Resample.

Resample Image
From here, the user can either choose to modify the existing TIN or create a new TIN with the resampled data.
The Step Value change be varied from 2 to 10, depending on the final size of the output.

For example:
Original TIN TIN Resampled Step 2
 		TIN Resampled Step 10
Approximate File Sizes of Exported TIN
10Mb
 5Mb
 1Mb



Tab Location(s): Project Tab
Tree Folder: TINes
Prerequisite: An Existing TIN