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I am profoundly disturbed by a request that asks me to develop an iPad app to measure the actual size of an object using camera.

It is simply not practical.

Translating 2D object into 3D is never easy. I either need extra hardware, or have to make a lot of assumptions (which will almost never hold true). Regardless I will need time.

However, the person who requested me to develop the app is adamant of his vision. And he tries to show that he is right by listing a number of existing apps that do similar jobs. He does not realize that all the apps he refers to has a rating lower than three stars, which means they probably do not do their job.

How can I convince this person that such an app simply cannot be done in a practical, single developer fashion? Is there a PhD thesis I can use as my defense?

YoYoMyo
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5 Answers5

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It's called "Forced Perspective"

Step 1. Go outdoors with a friend. Stand in front of a building.

Step 2. Take a picture so that the friend is really close to you and the building is really far away. Assure that the friend's head lines up with the top of the building.

Step 3. Ask your customer how tall it is, given just the photograph.

Do not specify what "it" is that the customer must define the height of. Let them assume -- or guess -- what part of the picture is relevant.

S.Lott
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Instead of trying to convince someone that something cannot be done try to analyze and determine what it would take to get this done.

When you calculate that it would take you alone 10 years and $1 billion the solution of what to do with the project will become obvious.

Karlson
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It's possible - plus, you could always do the processing remotely, only using the phone to collect data and display results. Beyond that, there's also nothing that says you're not able to mount a device to the phone's camera to split and offset 2D input, and then convert those two inputs into a 3D input.

As for app ratings, that's not really a solid basis for understanding the feasibility of a concept, or it's complexity.

Just have fun with the challenge, it's not the end of the world.

blunders
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Why not force the user to take the picture with a clearly displayed item of standard size next to the item being measured; a penny for example.

It's probably not as good of a solution as your employer wants but explaining a solution like this would at least show you can make something happen.

As you start listing the limitations and compromises needed, he will surely back away from a project like this (unless you have very good and sizable team behind you)

brian
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Actually I'm not sure you are correct.
Provided the user assist the app it should be possible.

For example of a 1D measurement. Stand 1meter away from 1dm high object. Add this as user input to your app. Stand 1km from a mountain, add this as user input. Keep the same angle from the camera with both your 1dm object and the mountain. The app should calculate the height of the mountain easily.

I would suggest further studding Triangulation for implementation details.

You can take this further by placing your phone in a tripod and and have the object to be measured always at a known distance. This way everything can be pre calibrated and your app could by only counting the pixels in height and width tell you the 2d measurements of the object under inspection.

Community
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