# Sub-sign recognition to better interpret Road signs

**URL:** <https://forum.mapillary.com/t/sub-sign-recognition-to-better-interpret-road-signs/7352>\
**Category:** Imagery, data, and integrations\
**Created:** [August 30, 2023, 7:29am UTC](https://forum.mapillary.com/t/sub-sign-recognition-to-better-interpret-road-signs/7352 "2023-08-30T07:29:31Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![oxtrimo](https://avatars.discourse-cdn.com/v4/letter/o/c6cbf5/32.png) [@oxtrimo](https://forum.mapillary.com/u/oxtrimo)\
**Post date:** [August 30, 2023, 7:29am UTC](https://forum.mapillary.com/t/sub-sign-recognition-to-better-interpret-road-signs/7352/1 "2023-08-30T07:29:31Z")

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Hello everyone,

Mapillary is doing a great job, I hope be contributing soon to this project which I onyl recently came across.

One of my observations is that Mapillary doesn’t always detect sub-signs. E.g.: A parking sign is detected but it doesn’t detect the two-wheeler motor cycle sign right under the P sign.  
So it effectively only detects only 1 of the 2 street signs.

The result is the conclusion we can draw from mapillary is different from the reality:  
Only ‘P’ detected: parking  
but ‘P’ with subsign two-wheeler motor cycle : parking for motor-cycles only.

There are numerous such examples, like, 1. no-entry (well detected) vs no-entry other than bicycles (bicycles not detected in sub-sign)… 2. Speed limits that apply only to a particular types of vehicles 3. Speed limits that apply to all vehicles taking the exit… etc.

So my question is:

1. Why are sub -signs more often not detected than detected ?
2. The un-detected signs (sub-signs that caught my interest) are a result of the sign not being included in the official image recognition traning?

Thanks for your clarification 🙂

Cheers!