This document provides instructions for modeling a canal in VRML format using TIN in ArcGIS, including: 1. Creating polygons of different elevations in a shapefile 2. Creating a TIN from the shapefile 3. Exporting the TIN to a VRML file format

1. zzz
Institute of
Geology

2. Model a Canal using TIN in VRML Format
A canal can be modeled using following methods:
1. Create a new shape file of Polygon.
2. Edit it, with 2-3 polygons.
3. But of different dimensions.
4. Add a field of Z with Short Integer.
5. Enter a value of elevation, differently for each polygon.
6. Create TIN, using 3D Analyst Tool.
7. Open it in Arc Scene.
8. Export to scene 3D to VRML file format.
Arrangement_01:

3. Arrangement_02:
Attribute Table_01:
For elevation, add
1. “0” for small polygon, and
2. “50” for larger polygon.
Attribute Table_02:
For elevation, add
1. “0” for Polygon 1, and
2. “100” for Polygon 2.

4. Result_01:
Result_02:

5. Calculate the Elevation
The given figure is as follows:
Solution:
The elevation at point P(z), according to my understanding is:
P(z) = B + a(AB) + b(BC) …{in terms of Point}
P(z) = Z2 + a(Z2-Z1) + b(Z2-Z3) …{in terms of Elevation}
P(z) = Z2 + a(D-D4) + b(D2-D1) …{in terms of Distance}
Compare the coefficient of x,y,z values of P(z) to calculate its unknown value (z).
Where,
a,b are any two real numbers
D = D3 + D4

6. Break Lines
As the name implies they are linear features that are used to define and control the
behavior of them in terms of smoothness and discontinuity.
Difference between soft and hard break lines:
Serial
No.
Soft Break Lines Hard Break Lines
01. They are used to define the areas that
show no or less interruption in the
terrain.
They are used to define the areas
that show interruption in the
terrain.
02. They are generally not representing the
physical features.
They are generally representing the
physical features.
03. They are used to maintain the linear
features within the TIN
They are used to maintain the
boundary
04. They can have constant or varying z-
values
They have constant z-values
05. No sudden slope Used in sudden slope
06. Examples:
Political boundary, soil types etc
Examples:
Ridges, streams, shorelines etc
Soft Break Lines Hard Break Lines
LinLines

7. Delaunay Triangulation
The main points for this concept include:
1. This is used to create contiguous, non-overlapping triangles.
2. Avoid long and thin triangles by maximizing all the interior angles.
3. No vertex lies in the interior of any other triangle.
4. It is a proximal method.
5. Maximizes the smallest interior angle.
6. The circle must pass through all 3 vertices of triangle.
7. It is a set of points satisfying the condition of empty circle.
8. Outer polygon is always a convex hull.

8. 9. For those points that lie on the same line there is no Delaunay triangle.
10. Triangles are kept equi-angular as possible so to ease the calculations.