B How to find the objects' areas in this photo in mm^2?

[Rev. Cheeseman]

Hello, how to find the area in mm2 for both bone cross sections? Are there any online applications that allow us to instantly calculate areas? Thank you.

 

[berkeman]

What are your thoughts on this? There are at least a couple ways that I know of to do this, but it would be better if you gave us your thoughts first. What accuracy is required for this?

 

[Rev. Cheeseman]

What are your thoughts on this? There are at least a couple ways that I know of to do this, but it would be better if you gave us your thoughts first. What accuracy is required for this?

Sorry, I don't understand because I only want to find the cross sectional areas for both bone cross sections. The right bone cross section seems to be bigger than the other but what about their cross sectional areas in mm2? Maybe the areas for both are the same?

 

[berkeman]

Does each little square in the figure represent $1mm^2$?

 

[phinds]

Sorry, I don't understand because I only want to find the cross sectional areas for both bone cross sections. The right bone cross section seems to be bigger than the other but what about their cross sectional areas in mm2? Maybe the areas for both are the same?

You did not respond to Berkeman's statement

it would be better if you gave us your thoughts first.

Which was a polite request that you follow the forum rules and show us what effort you have made to solve your problem.

 

[Rev. Cheeseman]

Does each little square in the figure represent $1mm^2$?

No. It is just a grid background that I enabled in Microsoft Paint.

 

[Rev. Cheeseman]

You did not respond to Berkeman's statement

Which was a polite request that you follow the forum rules and show us what effort you have made to solve your problem.

I can't solve it because I don't know how to find the area in mm2 for both cross sections.

 

[berkeman]

Well then how are we supposed to find the cross-sectional area in $mm^2$?

 

[Rev. Cheeseman]

Well then how are we supposed to find the cross-sectional area in $mm^2$?

Wait, I'll try another way to make grids so everyone can get what I want to find

 

[berkeman]

Wait, I'll try another way to make grids

That would help. BTW, if you just need to know which one has more cross-sectional area, there is a way to do that without a grid. You can even obtain the ratio of the cross-sectional areas using that technique.

Just to verify -- the center portions of the bone diagrams are open, and don't contribute to the cross-sectional areas, right?

 

[Lnewqban]

These may help:
https://www.sketchandcalc.com/

http://www.math-mate.com/chapter28_1.shtml

https://byjus.com/maths/area-of-irregular-shapes/

 

[Mark44]

No. It is just a grid background that I enabled in Microsoft Paint.

If you don't know the dimensions of the two images, you can't find the area. One thing to do would be to get the widths of each bone cross-section, and then figure out the size of each square on your grid relative to the width of each bone cross-section. Once you have this figured out, count how many squares each bone section covers, not counting the hollow part in each.

 

[robphy]

Hello, how to find the area in mm2 for both bone cross sections? Are there any online applications that allow us to instantly calculate areas? Thank you.

https://imagej.net/ij/
has an online version.
https://imagej.net/ij/docs/menus/analyze.html

But, as others have said, you need to calibrate a scale.
Without one, the best one can do is get the "area fraction" (the terminology used in imageJ).

 

[Rev. Cheeseman]

That would help. BTW, if you just need to know which one has more cross-sectional area, there is a way to do that without a grid. You can even obtain the ratio of the cross-sectional areas using that technique.

Just to verify -- the center portions of the bone diagrams are open, and don't contribute to the cross-sectional areas, right?

Yes, the hollow center is excluded. Only the cortical bone.

 

[Rev. Cheeseman]

https://imagej.net/ij/
has an online version.
https://imagej.net/ij/docs/menus/analyze.html

But, as others have said, you need to calibrate a scale.
Without one, the best one can do is get the "area fraction" (the terminology used in imageJ).

I see, thank you so much.