EOIR Spatial Properties

Choose which two optical parameters are inputs, used to calculate a third parameter. The pairing options on the shortcut menu are:

• Field-of-View and Detector Pitch
• Field-of-View and Number of Pixels
• Number of Pixels and Detector Pitch

Enter the following values:

• Horizontal Half Angle is half the angular extent of the horizontal field of view. You can choose the units. The default is 45 degrees. For EOIR, horizontal is defined as the angle from the boresight (Z) direction to the edge of the sensor in the YZ plane of the sensor's coordinate system.
• Vertical Half Angle is half the angular extent of the vertical field of view. You can choose the units. The default is 45 degrees. For EOIR, vertical is defined as the angle from the boresight (Z) direction to the edge of the sensor in the XZ plane of the sensor's coordinate system.

EOIR uses these to determine the full angular extent of the sensor field of view (FOV). This property is not available for Input = Number of Pixels and Detector Pitch.

Enter the number of sensor pixels in the field of view in the horizontal and vertical directions; the default is 200.0 for each. The number of pixels is limited to 1000 x 1000, to prevent an out-of-memory issue. By default, EOIR oversamples all images by four times. For example, a 1000 x 1000 image, rather than resulting in one million pixels, will produce 16 million simulated pixels because it is oversampled in both spatial dimensions. EOIR does this to properly capture higher spatial frequencies that could potentially be aliased.

If you are using a high-memory machine, you can set the environment variable AGI_EOIR_HIGH_MEMORY to create up to 5000 x 5000 pixels. For limited machines, setting this environment variable may risk memory issues.

The sensor model uses an ideal spatial response, which is unity within the IFOV (projected pixel area) and zero outside the IFOV. Each sensor pixel is, by default, oversampled four times in each direction, for a total of 16 samples per sensor pixel.

You can change the amount of oversampling that EOIR performs by setting the environment variable AGI_EOIR_SENSOR_OSF to one of these values: 1x, 2x, 4x, 8x, 16x, or 32x. Smaller values will result in faster processing speeds but lower-fidelity spatial simulation and also artificial spatial artifacts. Larger values will result in slower processing speeds but higher-fidelity spatial simulation and reduced spatial artifacts.

This property is not available for Input = Field-of-View and Detector Pitch.

These are horizontal and vertical physical dimensions of a pixel at the focal plane. Enter values for the following parameters:

• Horiz Pixel Pitch is the physical horizontal dimension of a pixel at the focal plane, in um.
• Vertical Pixel Pitch is the physical vertical dimension of a pixel at the focal plane, in um.

This property is not available for Input = Field-of-View and Number of Pixels.