KAPTURE is piece of software that calculates the optimal exposure for each UAV image and allows images to be triggered by the autopilot.
KAPTURE requires a Canon camera with CHDK installed on a bootable SD card.
For operation with a Pixhawk autopilot running APM 3.3+ a special trigger cable is required together with a source powering the central pin of the AUX output rail with 5V.
KAPTURE is based on the KAP UAV Exposure Control Script Version 3.5.
KAP UAV is a CHDK script to calculate optimal exposure for UAV images with user defined preferred values and ranges for shutter speed (Tv), ISO speed (Sv), and aperture (Av) settings.
An overview of the features and settings can be found at the KAP UAV web site (http://chdk.wikia.com/wiki/KAP_UAV_Exposure_Control_Script).
The major difference between KAPTURE and KAP UAV is in logging. KAP UAV logs almost any relevant camera setting while KAPTURE (only) logs detailed information about shot time which is required in Mavis.
KAPTURE is developed to be operated in „USB OneShot“ mode. OneShot takes one picture each time the USB power is pulsed from the autopilot.
The following parameters must not be changed for proper operation together with Mavis.
- USB Shot Control – OneShot mode
- Focus @ Infinity – Yes
To adjust the exposure settings the following parameters can be adjusted for specific cameras and setups:
- Exposure Compensation
- Start Delay Time (sec)
- Tv Min
- Target Tv
- Tv Max
- Av Low
- Av Target
- Av Max
- ISO Min
- ISO Max1
- ISO Max2
- Allow use of ND filter?
- Zoom position
Same as USB Shot Control and Focus@Infinity, the following settings should not be changed from the defaults:
- Shot Interval
- Total Shots
- Power off when done?
- Display Off?
- Video Interleave
- Video Duration
- USB Timer Precision
- USB Timeout
Camera settings (Canon S110)
- Camera mode P
- DR Correction Off
- ISO Auto
- White Balance Auto (AWB, except when using a target)
- My Colors Off
- Braketing/BKT Off
- Continuous Shooting Off (Single Shot)
- Self-Timer Off
- Metering Method Center Weighted Avg.
- ND Filter Off
- Continuous AF Off
- Tracking AF Off
- Image Ration 4:3
- Image Format JPEG
- Image Size 12M 4000×3000
- AF Frame Size Normal
- Digital zoom Off
- AF-Point Zoom Off
- Servo AF Off
- Continuous AF Off
- Touch Shutter Off
- AF-assist beam Off
- MF-point zoom Off
- Safety MF Off
- Flash (all) Off
- ISO Auto Settings 1600
- High ISO NR Low
- Wind filter Off
- Blink detection Off
- IS Mode Shoot Only (Or Off depending of the UAV setup / vibrations)
- Date Stamp Off
- Face ID Off
- Review Off
- File Numbering Auto Reset
- Create Folder Daily
- Lens Retract 0 sec.
- Auto Power Down Off
APM / Pixhawk settings
In the full parameter list in Mission Planner just the following:
- CAM_TRIGG_TYPE must be set to 1 (Relay)
- CAM_DURATION must be set to 1
- CAM_TRIGG_DIST should be set to 0 for planning survey missions with Tower
- The RELAY_PIN (50-55) depends on where you plug in the Trigger Cable and which Autopilot * you use (Pixhawk, AUAV-X2, DroPix,…)
- If you want to be able to trigger the camera via a RC Channel set the corresponding Channel * Option (e.g. CH7_OPT) to 9
- To log all relevant data set the LOG_BITMASK to 190462.
Be careful when setting the navigation speed (WPNAV_SPEED) for auto missions. It should not be too fast for the camera which will result in missing images. Georeferencing with Mavis works anyway but the overlap is reduced if images are missing. For example when WPNAV_SPEED is set to 500 cm and you give the camera 2 seconds for each shot the minimum flight altitude is 46 m to guarantee an overlap of 80 % using a Canon S110.
CHDK and KAPTURE installation
CHDK is a firmware enhancement for some Canon cameras providing additional functionality but makes no permanent changes to the camera.
To install it follow the instructions at the CHDK website.
- Download and run Stick.
- Follow the instructions to install CHDK on an empty SD card.
- Copy KAPTURE to [SDCard]:\CHDK\SCRIPTS
Lock the SD card, insert it into the camera and turn the camera on. Press the MENU button.
To navigate use the FUNC SET, the surrounding Buttons and the MENU button.
Navigate to the Script Menu then:
- Press Load Script from File and navigate to and select KAPTURE.lua
- Set the Script Shoot Delay to 0
- Set Autostart to ON
- Enable Restart on Lua error
Navigate to the CHDK Settings Menu then:
- Navigate to Remote Parameters
- Enable Remote
- Set Switch Type and Control Mode to None