Misalignment for CountryMapper, DMC-4, TerrainMapper-2 and TerrainMapper-3
Misalignment Flight Pattern for Nadir Sensors
All sensors equipped with a nadir-looking camera—whether a single camera head or a composite-frame multi-camera subsystem—and whether or not they include LiDAR, utilize a “nadir-only” flight plan. This plan follows a simple four-line pattern.
This pattern can be used to perform a misalignment calibration on the entire sensor or specifically on the LiDAR or image module.
Below is a brief description of the flight line pattern used for nadir-only imaging systems, as well as for the LiDAR component of hybrid imaging/LiDAR systems:
Two pairs of opposing flight lines at right angles.
The typical orientation features two north-south lines and two east-west lines.
The line length is set long enough to create a fully overlapping region in the center of the cross pattern (refer to the darker purple area in the illustration below).
An optimal Misalignment Flight Area will have the following attributes:
contain large buildings such a warehouses or sports areas, buildings with sloped roofs are ideal
contain mainly hard solid surfaces like asphalt, concrete, bare soils, and/or short grass
should not contain large areas covering dense canopy, high vegetation or water bodies
have well known GCPs which can be used to checking absolute accuracy
Hyperion2+ based Systems (TerrainMapper-2 or CityMapper-2 LiDAR only)
Line Settings for Hyperion2+ based systems - Nadir Misalignment Plan (H2+) | |||||
|---|---|---|---|---|---|
Line name | Line Direction [deg] | Scan Pattern | Used Scan Rate [Hz] | Target SNR | Min Fwdlap [%] |
NS03_2000C | 0 | Circle | 70-100 (Auto-Adjust) | 12 | 80 |
SN03_2000F | 180 | Flower* | 150 | 7.1 | 80 |
EW04_2000C | 270 | Circle | 70-100 (Auto-Adjust) | 12 | 80 |
WE04_2000F | 90 | Flower* | 150 | 7.1 | 80 |
General line settings for Hyperion2+ based systems - Nadir Misalignment Plan (H2+) | ||||||||
|---|---|---|---|---|---|---|---|---|
Pulse Rate [Hz] | FOV [deg] | Max Alt AGL [m] | Speed [kts] | Noise Suppression | Ch. Threshold | Image Fwdlap [%] | Line Length [km] | Multi Pulse Mode |
~480,000 (Auto Adjust) | 40 | 2000 | 110 | Medium | 150 | 80 | 5 | 5-7 |
Verification Lines for Hyperion2+ based systems - Nadir Misalignment Plan (H2+) | |||||||
|---|---|---|---|---|---|---|---|
Line name | Line Direction [deg] | Scan Pattern | AGL [m] | Used Scan Rate [Hz] | PRF [Hz] | Target SNR | Min Fwdlap [%] |
V01_2000C ** | 270 | Circle | 1,500 - 2,500 | 150 (Auto Adjust - Gateless) | 1,000,000 - 2,000,000 | 12 | 80 |
V02_2000C ** | 90 | Circle | 1,500 - 2,500 | 150 (Auto Adjust - Gateless) | 1,000,000 - 2,000,000 | 12 | 80 |
Hyperion3+ based Systems (CountryMapper, TerrainMapper-3)
specific line settings for Hyperion3+ based systems - Nadir Misalignment Plan (H3+) | |||||
|---|---|---|---|---|---|
Line name | Line Direction [deg] | Scan Pattern | Used Scan Rate [Hz] | Target SNR | Min Fwdlap [%] |
EW01_1700E | 270 | Ellipse*** | 46.5 | 7.3 | 80 |
WE02_1700C | 90 | Circle | 87 | 7.3 | 80 |
NS03_1700E | 180 | Ellipse*** | 127 | 7.3 | 80 |
SN04_1700C | 0 | Circle | 166.7 | 7.3 | 80 |
General line settings for Hyperion3+ based systems - Nadir Misalignment Plan (H3+) | |||||||
|---|---|---|---|---|---|---|---|
Pulse Rate [Hz] | FOV [deg] | Max Alt AGL [m] | Ground Speed [kts] | Noise Suppression | Channel Threshold | Image Fwdlap [%] | Line Length [km] |
1,200,000 | 60 | 1700 | 110 | Medium | 125 | 80 | 5 |
IMPORTANT
Hyperion2+ misalignment flight lines must be recorded with Gated Mode. Disable Gateless MPiA recording mode option in Leica Aeroplan for all Hyperion2+Misalignment flight lines. Gateless MPiA mode can be used for Hyperion2+ verification lines.
Verification Lines for Hyperion3+ based systems - Nadir Misalignment Plan (H3+) | |||||||
|---|---|---|---|---|---|---|---|
Line name | Line Direction [deg] | Scan Pattern | AGL [m] | Used Scan Rate [Hz] | PRF [Hz] | Target SNR | Min Fwdlap [%] |
V01_2000C ** | 270 | Circle | 1,500 - 2,500 | 166.7 (Auto Adjust) | 1,000,000 - 2,000,000 | 7.3 | 80 |
V02_2000C ** | 90 | Circle | 1,500 - 2,500 | 166.7 (Auto Adjust) | 1,000,000 - 2,000,000 | 7.3 | 80 |
DMC-4
general line settings for DMC-4 - Nadir Flight Plan **** | ||
|---|---|---|
Max Alt AGL [m] | Ground Speed [kts] | Image Fwdlap [%] |
1700 | 110 | 80 |
* in case of a installation with optical window, replace the Flower pattern with Circular
** LiDAR verification lines - use of project settings is recommended or with higher PRF and Scan Rate as the Misalignment lines
*** in case of a installation with optical window, replace the Ellipse pattern with Circular
**** for DMC-4 the same lines as for TerrainMapper-3 can be used