I’m wondering if it could be possible to give a rough estimate of object sizes in photos (on the order of 5 cm to 3 m). This could be helpful to better identify some species or perhaps train AI models on this data?
What do you think?
1 Like
The measure app on an iPhone uses the LIDAR to take its readings and it’s not very accurate for smaller things.
It’s ok for estimating sizes of medium sized objects like furniture and the like, but not very good for small things.
It’s difficult to find any actual numbers on accuracy from Apple, they seem to be very reluctant to make that information publicly available, but the accuracy range appears to be between 2-20%, with the accuracy decreasing the smaller an object is, hence the range. 1-2 cm error appears to be standard, but sometimes it’s more depending on conditions and user error.
In short, yes, you can use the LIDAR to measure things, and that function is built into the iPhone in the form of the Measure app, but it’s not meant to be a precise measuring system. As a result, for organisms in the size range you’re talking about can often have their size estimates as accurately or more by eye simply by paying attention to the context of the image and the other things in it.
A common thing people do to facilitate measurement in photographs is to include something that’s a fixed reference. Common things used for this purpose are a card with a scale on it, a coin, a pen, a pocket knife, etc.
7 Likes