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- Exposure intervals for the Red, Green and Blue channels is a function of the light intensity of the LEDs.
- Led intensity for the three channels is a function of the LED spectrum. Cold lights 65K are very blue while warm lights 55k are reddish. Neutral light is preferred where RGB are nearly equal but all leds are variable. Generally red is the lowest intensity and will require the longest exposure time. That is why in the above procedure we start with red, but you should always start with lowest intensity channel.
- Intensity is also a function of the F-stop. The smallest F-Top is preferred because it gives the greatest depth of focus but also lowers the intensity.
- Intensity is also a function of how closely coupled the lights are to the core surface but for practical reasons we need to keep a minimum clearance for safe operations.
- Don’t forget to check that all of the lights are evenly illuminated or even on. One led can fail without affecting these other. Don’t ever look at the leds directly!
- Line rate must be greater (20us) than the red, green and blue exposure rates set in the above procedure.
- The shorter the line rates the faster the image can be scanned.
- If you move the track faster than the scan rate you will see dropped lines in your image.
Pre 2019 SHIL Light Array
Please see the Pre 2019 SHIL Light Array info here.
C. Set Measurement Parameters
a) Instrument
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Setup
- DAQ > Image Capture Motion Setup (Figure 41)
Figure 41. Image Scan Setup window
2. Instruments > Camera: General Setup (Figure 42)
Figure 42. General Camera Setup window
3. Instruments > Camera: JAI Camera Setup (Figure 43).
Figure 43. General Camera Setup fixed Settings
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Camera Speed is calculated during the calibration procedure. The camera speed set must be lower than the speed determined by the calibration or else the camera will start 'dropping lines'. Dropped lines means the camera is moving too quickly to calculate the RGB and offsets at the bottom of the core will return values of '0'.
Adjust Camera Speed1.
- Go to DAQ > Image Capture Motion Setup (Figure 46).
Figure 46. Select Image Scan Setup window
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Figure 49. Image CROP window
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b) 360 Imaging Hard Rock
The SHIL can be used to image the external surface of whole round hard rock cores in order to assemble a 360° composite image of the whole round. Oriented rock pieces are imaged after they have been binned and the structural scientist has marked the split lines on the pieces. Using the custom whole round scanning tray, the whole round core surface is imaged four times at the 0°, 90°, 180°, and 270° orientation from the splitting line. The Imaging Specialist will download the images and assemble a composite image from the four scans and upload the composite separately.
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