> For the complete documentation index, see [llms.txt](https://gryfn.gitbook.io/gryfn-hardware/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gryfn.gitbook.io/gryfn-hardware/support/gobi-user-manual/data-collection.md).

# Data Collection

The following articles on Data Collection briefly discuss the method in which each sensor collects data, as well as some best practices for maximizing data quality from each sensor integrated in GRYFN Gobi.

{% content-ref url="/spaces/q2hGbYGESpVDi0Hbli0q/pages/neC6RoDR3pLjd1J7aAg7" %}
[Flight Planning Calculator](https://gryfn.gitbook.io/gryfn-operations/operations/flight-planning/flight-planning-calculator)
{% endcontent-ref %}

***

## Sensor Methodology

<details>

<summary>SBG Quanta Micro</summary>

The SBG Quanta Micro will initialize and set its position and elevation after a brief time receiving satellite signals, typically within 60 seconds after GOBI receives power from the aircraft. Gobi WebUI reports elevation from the Quanta Micro for altitude triggering purposes.&#x20;

When **Start Mission** is pressed in the Gobi WebUI, SBG Quanta Micro will set the ground elevation at whatever the current estimation is, and begin recording data. When an altitude triggering method or option is selected, ground-set altitude will be displayed in the status bar.

Prior to the starting the survey, a Dynamic Alignment Procedure for SBG Quanta Micro must be performed. The Dynamic Alignment Procedure must also be performed immediately after survey conclusion, prior to landing.

Users should perform the dynamic alignment procedure as close as possible to the survey start point, and immediately after the survey end, while outside the capture polygon.

The Dynamic Alignment Procedure shall include:

* 1-2 Figure 8 maneuvers

</details>

<details>

<summary>LiDAR &#x26; Frame Camera</summary>

The Ouster LiDAR sensor and RGB frame camera start in an idle state when GOBI receives power from the aircraft.

After pressing the **Start Mission** button in GOBI WebUI, the sensors are "primed" for data collection. Both sensors will adhere to the capture methodology selected in the Missions tab. For more information on the available options, see [Missions](/gryfn-hardware/support/gobi-user-manual/embedded-software/missions.md)

</details>

<details>

<summary>Headwall Nano HP</summary>

The Headwall Nano HP VNIR sensor requires in-field setup for each flight. These parameters include frame period/framerate, gain mode, exposure, and capture polygon.

### Frame Period

The sensor's frame period is a measure of how fast each frame (row of pixels) should be captured. This value will directly correspond to flight speed, as we must plan for the sensor to capture frames at (or faster than) the rate at which the aircraft traverses those frames.

The Headwall Nano HP has a maximum framerate of \~250 Hz, which equates to a 4ms frame period. GRYFN typically recommends 10-20% oversampling to account for aircraft pitch/speed instability to limit the number of missed frames.

### Exposure & Gain Mode

Exposure, or more appropriately Exposure Time, is a measure of how long we expose the sensor array to light for each captured frame. This value will determine how "bright" our image is by controlling how much time we allow energy to enter the sensor array. The goal for maximizing data quality should be to set exposure to the maximum saturation level possible without "clipping" any incoming spectral information.

### Capture Polygon

Users must upload a polygon file to the sensor that act as lateral bounds for data capture. Data will begin collecting when GOBI is inside the GPS polygon AND has exceeded the data triggering threshold (20m by default).

Please see your aircraft's [UAS Quick Start](https://gryfn.gitbook.io/gryfn-operations/uas-quick-start) guide in our [GRYFN Operations Wiki](https://gryfn.gitbook.io/gryfn-operations/) for building a GPS Polygon.

</details>

***

## Best Practices

GRYFN recommends a minimum flight speed of 2m/s and maximum flight speed of 8m/s for hyperspectral data collection. This is because the limited stability at slow speeds, and intense pitch at high speeds of cause issues with hyperspectral data quality.

## Area Coverage

Maximum area coverage estimates in ideal weather conditions, limited movement between study areas, efficient operators, unlimited battery sets.

### DJI M350

| ALTITUDE | Per Flight | Per Day (4 Hour Window) |
| -------- | ---------- | ----------------------- |
| 30m      | 7.5 Acres  | 45 Acres                |
| 60m      | 25 Acres   | 150 Acres               |
| 120m     | 60 Acres   | 360 Acres               |