DTM Errors

When forming triangles, there are a few potential problems, such as duplicate points. You will be informed when these problems occur by a dialogue box. This informs you how many problems there are and gives you the option to generate a text report or to display them graphically in the dedicated CAD backcloth for further examination. If you elect to plot the errors by checking the Plot Errors button, a mixture of CAD points and lines will be generated on a layer called DTM ERRORS in the dedicated CAD backcloth.

Duplicate Pts

This problem arises where two or more points have the same co-ordinates in plan. A CAD point will be generated in pen number 1, usually red.

Pts Over Lines

This problem arises where the point to be included is directly over the top of a line feature
segment that has already been forced into the model. Three CAD points and a CAD line will be
generated in pen number 2, usually yellow.

Lines Over Pts

This problem arises where a line feature segment that is being forced lies directly over a point which has already been included. Three CAD points and a CAD line will be generated in pen
number 3, usually green.

Crossings This

problem arises where a line feature segment that is being forced intersects with a line
feature segment that has already been forced. Four CAD points and two CAD lines will be generated in pen number 4, usually cyan.

Too Complex

This problem arises when either geometric conditions cause the algorithm to fail or where the data is ill-conditioned in that an attempt is made to force a feature segment whose length is
significantly longer than is the norm for the current model. Two CAD points and a CAD line will
be generated in pen number 5, usually blue.