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Lane Tracker Architecture |
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used in the Quick Color Cam TC-236 socs043a.pdf 284kb |
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TC-286 Brief Specs |
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Next-Gen Lane Tracker will be HybridThe next generation Lane Tracker will be a duel mode hybrid, combining two different architectures: one for daylight and one for night time.The camera topology consists of a single color CCD area array, capable of randomly addressable scan lines; a day/nite filter selector; a relay lens system; and the taking lens (front glass). Attached in close proximity and alignment will be the special spread-beam LASER illuminator (for night time). The daylight approach uses the first three active scan lines of a NTSC tri-color CCD area array. The image data from the array's R, G, B, outputs will be processed for Color Space Translation such that only HUE is extracted and used for White/Yellow Lines detection. This approach has among its properties, the exclusion of vehicle shadowing from the White/Yellow Line boundary detection problem. That is to say, the confusion between longitudinal /near parallel vehicle shadowing and White/Yellow Line edge boundaries has long been a problem requiring lots of DSP processor time. A second property is that it utilizes ambient light, reducing the complexity of the LASER only based approach. The night time line detection system utilizes the LASER only based approach found in the previous generation Lane Tracker. In this approach, unlike the aforementioned first gen lane Tracker, the linear CCD array is replaced with the color R,G, B, area array of the daytime system. An examination of the spectral plot of the color CCD array reveals a high sensitivity to the LASER wavelength, 790nm, in the RGB filter's NIR "pop-up" region. |
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| The Ideal Sensor
The ideal color area array sensor would have randomly addressable scan lines, such that the active image field could start at some arbitrary selected active scan line and either complete the field, or truncate the scan to from the very next line or any contiguous group of lines, i.e., the field could be from 1 line to 242 lines in length (typically, 3 lines). The practical reasoning behind this approach are several: 1) random
intermittent full image views of the roadway scene could be captured; 2)
this would allow greater control on light integration time, i.e., several
line times to multiple field intervals n x 16.667msec.
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| The less-than-ideal NTSC Sensor
Some standard NTSC RS-170A, CCD sensors can be used for this approach by, asynchronously restarting the frame transfer clock . The deficiency in this approach is the latency of the first 20 scan lines that make up the vertical interval. This would mean a fixed delay of 1,270 usec ( n x 63.5 usec) before active imaging takes place. Conclusions
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| HUE Extraction
1) Data Translation RGB - HSI Convertor DT7910 & ROM DT7971. 2) A real time SUM of Vectors circuit--analog or digital-- can also do the RGB - HSI conversion. Because this a radiometric not a photometric problem, the R G B inputs can have any weight, e.g.., equal weights R = 0.33, G = 0.33, B = 0.33. |
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| Histogram of section of Yellow Line | Histogram of section of Yellow Line--Color Inverted |
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| Histogram of section of White Line | Histogram of section of White Line--Color Inverted |
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| Histogram of section of Asphalt Pavement | Histogram of section of Asphalt Pavement--Color Inverted |
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Combination Camera |
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| Combination Camera with Dual Filter Selector
Filter F1 is a 3 stage Dielectric Optical Bandpass Filter
Fc = 790 nm, HPWL = 10 nm;
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Hi-Res BCMD Image Sensor for NTSC Color Applications. |
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For Your Very
Own DataSheet (socs059.pdf ~125Kb)
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| Subject: Addressable line-scan part from TI Date:
Mon, 06 Jan 1997 From: Scott Johnson <sojo@ti.com>
Glen, After speaking with our CCD group, I found out that our TC286 has the addressable line scan incorporated into it. The datasheet is in our 1996 Area Array Sensor databook, or I have attached an electronic copy if you don't have the book. It looks like we will have preliminary samples in March, with projected production in the August timeframe. It looks like the part will sell for somewhere around $62. Please refer to one of our authorized distributors for an exact quote or give us a call if you have further questions. Our phone number is (972) 644-5580. Regards, Scott Johnson Product Information Center |
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