回复： coordinate transform--robot

[Time_Walker]

Hello sir:

Regarding "Simple Calibration.vi", i had a question:

why they use "0.15" for "IMAQ set simple calibration2 vi"? it mean 1pixel=0.15Millimeter? but actually i got 1pixel=0.083Millimeter from picture's resolution. i don't understand these relationship. is there any help? thanks.

[Time_Walker]

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Time_Walker 已写：

Hello sir:

Regarding "Simple Calibration.vi", i had a question:

why they use "0.15" for "IMAQ set simple calibration2 vi"? it mean 1pixel=0.15Millimeter? but actually i got 1pixel=0.083Millimeter from picture's resolution. i don't understand these relationship. is there any help? thanks.

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any help?

[udka]

Yes, based on your image setup and calibration grid image it can vary.
-Yes it means one pixel is equivalent to 0.15mm in X direction and 0.15mm in Y direction

[Time_Walker]

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udka 已写：
Yes, based on your image setup and calibration grid image it can vary.
-Yes it means one pixel is equivalent to 0.15mm in X direction and 0.15mm in Y direction

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but actually i got the result from picture's resolution :

the resolution for picture is 300dpi. it mean 300pixels/inch, 1inch=25.4Millimeter.

300pixels/25.4Millimeter.

1pixel=0.083Millimeter.

why it is so huge different with "0.15mm" specified in picture? "0.15mm" is an arbitrary setting for demostration? when we need to set "X step", "Y Step" parameter in application, how to caculate it and set it?

[Hatef.fouladi]

you have to use sample target in your image that you know the dimensions of this sample

[Time_Walker]

one more questiion:

X Step and Y Step:

"Scaling factors are the real-world distances between the dots in the calibration grid in the x- and y- directions and the units in which the distances are measured. Use the X Step and Y Step elements of the Grid Descriptor control to specify the scaling factors." this is the definition in "https://zone.ni.com/reference/en-XX/help/370281M-01/nivisionlvbasics/perspective_and_nonlinear_disto..."

the following is the definition in the labview help for "IMAQ Calibration Target to Points - Circular Dots VI", "X Step corresponds to the width of a pixel in real-world units." it make me completely confused.

Any help ? which one is right? Any official explaination? thank you very much ~~~~

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Hatef.fouladi 已写：
you have to use sample target in your image that you know the dimensions of this sample

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[Hatef.fouladi]

witch part confused you?

[Time_Walker]

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Hatef.fouladi 已写：
witch part confused you?

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X Step and Y Step:

"Scaling factors are the real-world distances between the dots in the calibration grid in the x- and y- directions and the units in which the distances are measured. Use the X Step and Y Step elements of the Grid Descriptor control to specify the scaling factors." this is the definition in "https://zone.ni.com/reference/en-XX/help/370281M-01/nivisionlvbasics/perspective_and_nonlinear_disto..."

the following is the definition in the labview help for "IMAQ Calibration Target to Points - Circular Dots VI", "X Step corresponds to the width of a pixel in real-world units." 

The definition for X-step and Y-Step are the same? or they are different? i marked it with red color~

[Hatef.fouladi · Accepted solution]

sppose you have two point  with distance of 1 cm 
you  find out that this two point distance is 3 pixcel in image 
so if you check bellow image you have this 
x step 1
y stem 0,98
unit :cm