# Newly manufactured cars: tunnel of light **URL:** \ **Category:** Factual Questions\ **Created:** [May 2, 2022, 9:40pm UTC](https://boards.straightdope.com/t/newly-manufactured-cars-tunnel-of-light/963854 "2022-05-02T21:40:24Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [May 2, 2022, 9:40pm UTC](https://boards.straightdope.com/t/newly-manufactured-cars-tunnel-of-light/963854/1 "2022-05-02T21:40:24Z")
I frequently see pictured of new cars rolling off the assembly line, but they’re going through a tunnel of light. Here’s an example: [![](https://cleantechnica.com/files/2022/04/NIOET5.jpeg) ](https://cleantechnica.com/files/2022/04/NIOET5.jpeg) What the purpose of this? At one time, I thought it was just for marketing, but I see it on a lot of different vehicles. Also, the tunnels aren’t that short, which is what you’d expect if it was only marketing. So my guess is now that it’s something to do with the paint. Am I getting close? ---
**Author:** ![dolphinboy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dolphinboy/32/330_2.png) [@dolphinboy](https://boards.straightdope.com/u/dolphinboy)\ **Post date:** [May 2, 2022, 9:49pm UTC](https://boards.straightdope.com/t/newly-manufactured-cars-tunnel-of-light/963854/2 "2022-05-02T21:49:09Z")
I guess paint drying, but that’s not a factual answer. Just a guess. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [May 2, 2022, 9:55pm UTC](https://boards.straightdope.com/t/newly-manufactured-cars-tunnel-of-light/963854/3 "2022-05-02T21:55:13Z")
Surface quality inspection (after the car is painted), as shown in [this site](https://www.durr.com/en/products/paint-shop-application-technology/paint-quality-inspection/ecoreflect). ---
**Author:** ![AskNott](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/asknott/32/5790_2.png) [@AskNott](https://boards.straightdope.com/u/AskNott)\ **Post date:** [May 2, 2022, 10:05pm UTC](https://boards.straightdope.com/t/newly-manufactured-cars-tunnel-of-light/963854/4 "2022-05-02T22:05:09Z")
Yup. Not just for surface flaws, but making sure the color of various parts, which may have been painted in different plants, matches. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [May 2, 2022, 10:24pm UTC](https://boards.straightdope.com/t/newly-manufactured-cars-tunnel-of-light/963854/5 "2022-05-02T22:24:25Z")
OK, it’s for inspection of the paint job. But where are the inspectors? I never see any of them. There’s none in the picture above. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [May 2, 2022, 10:29pm UTC](https://boards.straightdope.com/t/newly-manufactured-cars-tunnel-of-light/963854/6 "2022-05-02T22:29:57Z")
I’m guessing they cleared out for the picture. There’s no one in the entire shot. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [May 2, 2022, 10:31pm UTC](https://boards.straightdope.com/t/newly-manufactured-cars-tunnel-of-light/963854/7 "2022-05-02T22:31:51Z")
They _may_ use an automated machine vision system, so there would be no people in the tunnel. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [May 2, 2022, 10:34pm UTC](https://boards.straightdope.com/t/newly-manufactured-cars-tunnel-of-light/963854/8 "2022-05-02T22:34:35Z")
True, but there would still be people in the vicinity keeping an eye on things even (especially) if those cars are self driving. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [May 2, 2022, 10:36pm UTC](https://boards.straightdope.com/t/newly-manufactured-cars-tunnel-of-light/963854/9 "2022-05-02T22:36:58Z")
I agree that for the purposes of those cool photos, all of the people left the area. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [May 2, 2022, 10:45pm UTC](https://boards.straightdope.com/t/newly-manufactured-cars-tunnel-of-light/963854/10 "2022-05-02T22:45:34Z")
Here’s another such picture: [![](https://i0.wp.com/electrek.co/wp-content/uploads/sites/3/2022/04/Rouge-Electric-Vehicle-Center_00-e1650975958625.jpg?w=1500&quality=82&strip=all&ssl=1) ](https://i0.wp.com/electrek.co/wp-content/uploads/sites/3/2022/04/Rouge-Electric-Vehicle-Center_00-e1650975958625.jpg?w=1500&quality=82&strip=all&ssl=1) Again no inspectors, so I gess they always get out of the way. Nor do I see any cameras, which would be needed for an automated inspection. ---
**Author:** ![jjakucyk](https://avatars.discourse-cdn.com/v4/letter/j/3d9bf3/32.png) [@jjakucyk](https://boards.straightdope.com/u/jjakucyk)\ **Post date:** [May 3, 2022, 1:09pm UTC](https://boards.straightdope.com/t/newly-manufactured-cars-tunnel-of-light/963854/11 "2022-05-03T13:09:03Z")
Taking photos with very bright (and/or very dark) areas may requires some compositing of different exposures to prevent lights from being blown out, creating halos or bloom, or affecting the exposure such that you can’t see anything even remotely dark. Compositing multiple exposures is much easier if there’s nothing moving, like people. Yes you can do it with a single shot and the right local adjustments, but the quality isn’t usually as good and you end up with more graininess in shadows.