MAPIR offers our compact Diffuse Reflectance Standard Calibration Target Package (T3-R50), which contains 4 reference standard targets of known reflectance. Diffuse and total reflectance percent measurements from 250-2500nm were made using multiple Shimadzu spectrophotometers incorporating an integrating sphere. The lambertian reflectance panels can be captured from any angle thanks to similar diffuse and total reflection properties, though capturing straight-on is recommended. Our computer vision software automatically finds the QR symbol in the target images and calculates the pixel to reflectance relationship using the known target material reflectance (data download here).
The reflectance targets are composed of a felt-like sheet material adhered to a plastic substrate. Care should be taken to ensure the targets are debris-free to produce the best calibration results, often a puff of air is all that is needed to clean them. The target's housing is made of durable, smoothed nylon plastic and the QR fiducial pattern material is a UV durable, laminated label.
Along one side of the target housing is a metric ruler and the other side contains an imperial ruler. A centering bubble level is located on the target housing hinge to assist with leveling. There are 3 standard 1/4-20 threaded brass inserts to allow you to easily attach the target to whatever you need to capture images of. Attaching to a tripod allows you to easily lift the target off the ground, keeping it cleaner.
The included neck lanyard allows for ease of carrying the lightweight 150g target package. The lanyard contains a push-button quick disconnect and metal finger ring for convenient handheld use. The neck lanyard also has an adjustable sliding cinch point, handy for wrist use as well.
|Package Model||Reference Target Dimensions||
Recommended Capture Distance (Survey3W)
||Recommended Capture Distance (Survey3N)|
|T3-R50||2.0" x 2.0" (50 x 50 mm)||8 in - 13 ft (0.2 - 4.0 m)||20 in - 33 ft (0.5 - 10.0 m)|
|T3-R125||5.0" x 5.0" (125 x 125 mm)||20 in - 33 ft (0.5 - 10.0 m)||40 in - 105 ft (1.0 - 32.0 m)|
To use the target, simply capture a photo of the entire open package, making sure the QR side and the 4 target side are visible. Try to make sure no harsh/dark shadows intrude on the white outer perimeter of the QR label, rotating the target as needed. The image of the housing hinge above shows shadows that are acceptable. Full capturing tutorial here.
Using our MAPIR Camera Control (MCC) or MAPIR Cloud software you can provide photos of this target package and the QR fiducial pattern should be automatically detected, regardless of 3D pose. The pixel values from the targets will be measured and calibration formulas will be calculated. The reflectance calibration will then be applied to the remainder of your images until a new target image is found (depends on MCC recalibration setting value). An unlimited number of target images can be used to correct your images for reflectance over time and across various lighting environments (i.e. cloudy days). Using the Analyze tab in MCC you can calculate the raster/index images (for example NDVI) and then apply a color map (LUT).
The T3-R50 was specifically designed to provide the best results in the smallest package size. Smaller size means much lower shipping costs, important for our international customers. It also fits much more easily into your gear bags and its lightweight yet durable design makes it convenient to carry with you or attach anywhere.
Total Closed Dimensions: 4.9" x 4.3" x 0.6" (12.6 x 11.0 x 1.6 cm)
Total Open Dimensions: 9.3" x 4.3" x 0.6" (23.6 x 11.0 x 1.6 cm)
Each Target: 2.0" x 2.0" (50 x 50 mm)
Weight: 5.3 oz (150 g) (+25g for lanyard)
(1) Diffuse Reflectance Standard Calibration Target Package (T3-R50), containing 4 measured reflectance standard targets and an identification QR label.
(1) Neck lanyard, with a quick disconnect feature allowing for handheld use as well.
Using our compact tripod you can easily keep the target off the ground, above high vegetation or wrap its flexible arms around trees and fences. The tripod includes a 360 degree adjustable and locking ball head that allows you to angle the target at the exact angle you need. Maximum height is 12 in (30 cm).