Advanced unmanned aerial vehicles for your professional applications.
Tetracam ADC Snap

4.995

Tetracam’s Ultra-Fast 90 Gram Multi-spectral Imaging System with Electronic Global Snap Shutter.

    If you are ordering Multi-spectral System for your READY TO FLY drone, you can choose whether you want to install the Multi-spectral System or not.
  • 0,00 €

Need Help? Contact Us Leave Feedback

Categories: , .

 The ADC Snap is housed in the same package as the ADC Micro. It has the same weight, power consumption and interface connections as the ADC Micro. The camera’s major difference is that it uses a 1.3 MPel electronic global snap sensor (1280 x 1024pixels). Unlike previous ADC systems, the ADC Snap exposes the entire image at the same instant in time. For this reason, this system does not experience rolling shutter problems. The ADC Snap’s exposure time is so fast that engineers in our labs use this camera to capture stop-action photos of fan blades on their desks. These stop action cameras operate at speeds comparable to industrial machine vision cameras.

The CMOS sensor in the ADC snap does not use a “rolling shutter” as do the CMOS sensors in other cameras of the ADC line. Instead, it uses an electronic global “snap” shutter. It also has much larger pixels and better NIR response. This means that the ADC snap does not have motion distortion in captured images, and that its’ exposure times are short enough to eliminate motion blurring in the image as well. Practically, this means that the ADC snap pictures can be taken at lower altitudes and/or higher speeds than the other cameras in the ADC family. The ADC Snap camera is ideal for use with fast or low-flying UAVs, especially fixed wing aircraft susceptible to pitch, roll or yawing problems.  It also means that the images will be easier to time with various mosaic building software packages. The implementation of the global electronic shutter in the ADC snap sensor produces raw images(images coming directly off the sensor) that have not had dark current noise removed. This is done later, when the images are transferred to a host computer.

The order of the pixels in raw images is also scrambled, from a conventional sensor point of view, and the pixels are reordered when transferred to the host as well. For this reason, the images taken by the ADC Snap camera have different file extensions than those of the rest of the ADC family. The unusual pixel order results in the appearance of vertical lines in the raw unprocessed image. This is because the red, green, and NIR pixels are grouped together in columns of four. Since the response of the three color filters is slightly different, green pixels appear brighter, while red and blue pixels are darker.

The image that is captured on the ADC Snap sensor is made up of 1280 x 1024 pixels (1.3 MPel). Images are stored along with metadata such as GPS coordinates and/or attitude information (pitch, roll and yaw) that is sent to the system through the ADC Snap’s serial interface (see I/O connections described below). Metadata helps users establish the ground location of each image.

The ADC Snap’s SD memory is easily accessible by the user. After missions are completed, users remove the Micro SD memory from the camera and transfer its contents to a host computer equipped with PixelWrench2, the software included with all Tetracam systems.

PixelWrench2 provides color processing of Tetracam RAW and DCM files, complex batch processing tools, a comprehensive suite of image editing tools and the ability to extract various vegetation indices such as NDVI from the captured images.

In addition to indicating plant stress, vegetation indices such as NDVI enable users to deduce information such as biomass, chlorophyll concentration in leaves, plant productivity and fractional vegetation cover as well as predict crop yield. Refer to System Application Notesfor descriptions of example applications.

Featuring 2GB standard storage (extensible to 16 GB), fast parallel processing, ultra-low power consumption, and simple menu-organized configuration and control, the ADC Snap contains a 1.3 mega-pixel sensor optimized for capture of visible light wavelengths longer than 520 nm and near-infrared wavelengths up to 920 nm.

The ADC Snap and its accompanying software, PixelWrench2, are ideally suited for capturing and analyzing multi-spectral images of crops, forests and other eco-systems. The ADC MIcro possesses a high-quality 8.43 mm lens. The lens focuses the light that enters the camera on to the system’s multi-spectral Snap Shutter image sensor.

Three filters atop the sensor limit the radiation that enters it to bands of green, red and near-infrared radiation equivalent to Landsat Thematic Mapper bands TM2, TM3 and TM4. These bands are the basis for the standard “false color” composite images that have become associated with multi-spectral imagery. They provide excellent early warning signs of plant stress and their use as indicators of other specific plant and soil conditions has been documented by scientists for decades.

The graph above shows the response of the sensor to different bands of light through the red, green and blue filters. A blue absorbing glass filter is used to eliminate the blue sensitivity, and the blue pixels in the sensor are used to measure NIR (Yellow Curve). The image is then processed in Pixelwrench2 to subtract the measured NIR from the blue and red bands to produce the final Red/Blue/NIR image

ADC Snap (with 8.43 mm Lens). Ground Resolution & FOV Examples

The ADC Snap enables users to gather information about vegetation at wavelengths traditionally monitored by satellites.  Only, flying in manned or unmanned aircraft, data gathered by the ADC Snap is captured at times completely determined by the user, independent of satellite latency, un-obscured by cloud cover and in images that show considerably higher detail than images captured from space (i.e., with resolutions measured in millimeters per pixel rather than meters per pixel).

The ADC Snap’s field of view (FOV) is laid out in a 4:3 format.  The horizontal angle of view for the system is 37.67 degrees.  The vertical angle of view is 28.75 degrees. When carried in a manned or unmanned aircraft, the field of view increases as the above ground level (AGL) altitude increases.

As the AGL increases, the camera’s ability to resolve individual details on the ground decreases.   With its standard 8.43 mm lens, when flown at altitude of 400 feet (122 meters) above ground level, this camera creates an image large enough to capture an area measuring 95 meters wide by 71 meters high at a resolution of less than two inches (46.3 mm) per pixel in a single shot.

Below is a table that shows the ground resolution and field of view for images gathered at various altitudes above ground.  PixelWrench2 contains an FOV Optical Calculator that enables determination of the system’s field of view and ground resolution for any user-specified altitude.  For operation in the field, this utility is also available as a free app that runs on Android cell phones.

Sensor & Lens Parameters

Object Distance

(Altitude Above Ground Level in meters)

Ground Resolution

in mm per pixel

FOV

(width x height)

in meters

The values shown at right were derived from the FOV (Field of View) Optical Calculator contained in Tetracam’s PixelWrench2 software (included with this camera) using the current values for this camera shown below:

Sensor Dimensions (mm):  6.59 x 4.9

Pixel Size (in microns): 5.0

Camera Lens Focal Length (mm):  8.43

122 m (~ 400 ft)

72.34

95.349 x 71.186

213.4 m (~ 700 ft)

126.54

166.782 x 124.517

365.8 m (~ 1200 ft)

216.91

285.89 x 213.441

915 m (~ 3000 ft)

542.58

715.115 x 533.895

Note: In order to view a larger composite image of an area of interest, users may purchase third party software that stitches multi-spectral images of adjacent areas captured by a Tetracam system together into a larger image mosaic.