Table of Contents

## What is Wulff net?

The net is a projection of a collection of great and small circles, which represent lines of latitude (small circles) and lines of longitude (great circles) on the sphere, as seen here: 3 great and 2 small circles.

## What is stereographic net?

The stereographic net or stereonet is the 3-D equivalent of a protractor. It is used to measure angles on the projection. To measure angles, we need to rotate the net relative to the tracing paper.

## How do you find a stereographic projection?

The stereographic projection of the circle is the set of points Q for which P = s-1(Q) is on the circle, so we substitute the formula for P into the equation for the circle on the sphere to get an equation for the set of points in the projection. P = (1/(1+u2 + v2)[2u, 2v, u2 + v2 – 1] = [x, y, z].

## Why is stereographic projection used?

So the stereographic projection also lets us visualize planes as points in the disk. For plots involving many planes, plotting their poles produces a less-cluttered picture than plotting their traces. This construction is used to visualize directional data in crystallography and geology, as described below.

## What is equal angle projection?

For the Equal Angle projection method, a line is drawn from the center of the top of the sphere (the zenith), to a point A on the sphere (a pole or a point on the great circle). The intersection of this line with a horizontal plane through the center of the sphere, defines the projection point B.

## Is stereographic projection a Homeomorphism?

Example: Stereographic Projection Stereographic projection is an important homeomorphism between the plane R 2 \mathbb{R}^2 R2 and the 2 2 2-sphere minus a point.

## Who invented the stereographic projection?

The stereographic projection was exclusively used for star charts until 1507, when Walther Ludd of St. Dié, Lorraine created the first known instance of a stereographic projection of the Earth’s surface. Its popularity in cartography increased after Rumold Mercator used its equatorial aspect for his 1595 atlas.

## Why stereographic projection drawing is used in crystallography study?

When all crystallographic low index directions intersecting the sphere in the southern hemisphere are drawn and projected to plane, a stereographic projection is constructed. This kind of projection preserves angles (but not areas), so it is possible to measure angles between crystallographic directions.

## What is Polar zenithal stereographic projection?

Polar Zenithal Stereographic Projection It is a perspective projection, with the source of light lying at the pole diametrically opposite to one at which the projection plane touches the generating globe.

## What is equal-area net?

equal-area net(Schmidt–Lambert net) A system of coordinates providing a two-dimensional representation of a three-dimensional object, which is used to display structural data graphically.

## What is 1st & 3rd angle projection?

To get the first angle projection, the object is placed in the first quadrant meaning it’s placed between the plane of projection and the observer. For the third angle projection, the object is placed below and behind the viewing planes meaning the plane of projection is between the observer and the object.