How to use the Brinno TLC300 in traffic surveys

The TLC300 has now fully replaced the old workhorse, the Brinno TLC200 Pro. Although it has taken a while to get the unit to match the performance of the old camera, The new TLC300 can be used with confidence on the majority of your traffic surveys.
To get the best out of the camera, it might be worth just looking at the key differences below:-

Feature	TLC200 Pro	TLC300
Sensor resolution	720P	1080P (quasi 720 with V2.23)
Processor	Standard	Brinno Design
Timer	Single event 24 hour	Single event 7 day
Power connection	Micro USB	C type
Operating life (4 x AA)	60 days Timelapse	100 days Timelapse
In survey Mode (ASAP)	36 hours	23 hours
Lowest capture rate	ASAP	3 images per second (V2.23)
Video output format	Avi	MP4
Form factor	TLC200 style	TLC200 style
HDR	Yes	No
Maximum file size	518Mb	4 Gb
Photographic settings	No	Yes

  

ASAP explained

Brinno’s ASAP function needs a little explanation to fully understand. The interval setting ASAP is vague to say the least. Its does not have a fixed capture rate but changes depending on picture content, speed of traffic and light level. On a good day with medium speed traffic and good light the camera can deliver up to 2.5 images per second - in the old days these were known as frames and recorded as frames per second (FPS) but its more accurate to call them images per second (IPS). However, on a bad day with low light and quickly changing images this can be as low as 1 image every 3 seconds!

This is due to a process known as conditional refresh. Essentially, the camera sensor is an array with many receptors known as pixels. These receptors individually charge up to different levels as light is focused on them via the lens. The pixels convert this light to a digital value and the value is transferred to the processor to be converted to an image within a video sequence. Depending on the sensor, there can be thousands of pixels all delivering different values many times per second. The sheer size of the data being dumped can swamp the processor and can slow the overall process. Brinno, like most camera designers, use conditional refresh to streamline the process. Each image (Frame) is captured at around 25 per second, and each image will have a unique value from the pixels within it. Each frame will have the same value if nothing changes within the frame, for example night time with no cars in the shot. If there are 4,000 pixels on the sensor and only half of them are seeing a change in their value during a particular sequence due to for examply a car moving through the middle of the view whilst the rest of the surroundings remain the same. Then only 2,000 values need to be recorded instead of 4,000 and with only half the processing. In other words the sensor only records changes between images. This is the conditional refresh and Brinno use it to get a faster capture rate for the camera.

The downside is that it is dependant on so many variables and if the survey is taken on busy roads in low light then the capture rate can vary drastically. This variation will cause different file sizes and video lengths as well as really mess up any automatic counter classification.

The TLC300

The TLC300 has a lowest capture rate of 3 images per second which is fixed and does not vary regardless of picture content or light level. To select this rate, go to the settings screen of the camera and select interval. Then select ‘custom’ and then set this to 00:00:00.

Then in advanced settings select daylight if the survey is being run in daylight and twilight if the survey includes any dawn/dusk activity. Do not use the nite (forgive the American spelling) at any time as this will affect the exposure setting and will only deliver ‘star trails’ instead of vehicles.

As the TLC300 has a whole host of other settings which will help reduce the file size, go to advance settings and select EV. Set this at 0 and the saturation setting to 50%.

Lastly, set the battery selection to Alkaline as the lithium setting can increase the current taken by the processer.

GDPR

Recent changes to the GDPR guidelines allow a 720P sensor to be used to store data to a local SD card for and still be exempt from potential breeches in personal data. This is due to the recent acceptance that facial recognition software needs a minimum resolution of 1080P.

The Brinno TLC300 is a 1080P camera. The Eugento traffic firmware only permits the camera to record at 720P resolution. If this firmware is removed or changed then the GDPR restrictions will apply.

As always if you have any queries, just get in touch...