Understanding the Incident Angles Layer Type

The layer type Incident Angles separates the data by ranges of incident angles. That means, one layer corresponds to one incident angles range.

Ranges are defined according to different factors:

  • The sampling of the layer: the sampling determines how many layer will be generated.
  • The type of integration: according to the integration type, the total integration angle is different.
    • In Planar integration, the integration is made in [0;90]
    • In all other integration, the integration is made in [0;180]

  • The Integration Direction in case of a Planar or Semi-cylindrical integration type.

    Rays are integrated in the different layers according to the Integration Direction. A ray with an angle theta in relation to the integration direction will be integrated in the layer min angle <= theta < max angle.

Planar Integration Case

The Planar Integration is calculated on an angle of integration included in [0;90] with 0 corresponding to the direction of integration.

The direction of integration is used to determine how pixels are oriented on the sensor plane. The direction of integration corresponds to the inverse of the normal to the pixels.

Example

The following example presents you two sensors with a planar integration type separated by incident angles.

The sampling defined is 6 meaning you will generate the 6 following layers:
  • Layer 0-15
  • Layer 15-30
  • Layer 30-45
  • Layer 45-60
  • Layer 60-75
  • Layer 75-90

In the figure 1, you can see that the Integration Direction determines how pixels are oriented, which therefore will generate different results according to the rays that will be integrated in each layer.

Figure 1. Integration Direction effect


In the figure 2, both Ray 1 and Ray 2 will be integrated in the Layer 60-75.

Figure 2. Rays Integration


Semi-Cylindrical Integration Case

The Semi-Cylindrical Integration is calculated on an angle of integration included in [0;180]; 0 being the arrow tail of the integration direction and 180 the arrowhead.

The Integration Direction of a Semi-Cylindrical integration is always parallel to the sensor plane.

Example

The following example presents you a sensor with a semi-cylindrical integration type separated by incident angles.

The sampling defined is 12 meaning you will generate the 12 following layers:
  • Layer 0-15
  • Layer 15-30
  • Layer 30-45
  • Layer 45-60
  • Layer 60-75
  • Layer 75-90
  • Layer 90-105
  • Layer 105-120
  • Layer 120-135
  • Layer 135-150
  • Layer 150-165
  • Layer 165-180

The ray 1 hits the sensor plane with a theta angle of 17° in relation to the Integration Direction. Therefore, it will be integrated in the Layer 15-30.

The ray 2 hits the sensor plane with a theta angle of 36° in relation to the Integration Direction. Therefore, it will be integrated in the Layer 30-45.

Figure 3. Rays Integration in Semi-Cylindrical Integration Type