Voxel Viewer About checkerboard pattern

masahiko shimizu

Guru 11235 points

Hi,

Could you give me information of the checkerboard pattern which is showed Figure 24 in Quick Start Guide, please?

Best regards,
Shimizu

over 8 years ago

0 Nithin Jose over 8 years ago

TI__Intellectual 1680 points

Hi Shimizu san,

We recommend using a checker board with odd no. of squares in one direction and even no. of squares in the other direction. There is no hard requirement on the dimensions of the squares. When you are using checker board for calibration, kindly make sure it occupies major part of the FoV.

Thanks and Regards

Nithin Jose

Texas Instruments

0 masahiko shimizu over 8 years ago in reply to Nithin Jose

Guru 11235 points

Hi Jose,

Thank you for your support.

I'm sorry. I am not good at English.

Could you tell me the mean of below your answer, please?

"We recommend using a checker board with odd no. of squares in one direction and even no. of squares in the other direction. "

Please see the attached. Which case is correct? 　

Best regards,

Shimizu

Ckecker board.pptx

0 Nithin Jose over 8 years ago in reply to masahiko shimizu

TI__Intellectual 1680 points

Hi Shimizu san,

Please find the attached image of a checker board for reference.

0 masahiko shimizu over 8 years ago in reply to Nithin Jose

Guru 11235 points

Hi Jose,

Thank you for your support.
I add one question.

There is "The checkerboard should be printed on A2 sized paper." at Quick start guide.
www.ti.com/.../sbou157.pdf

Must we use A2 sized paper?
If we make sure it occupies major part of the FoV, can we use more small paper?

Best regards,
Shimizu

0 Nithin Jose over 8 years ago in reply to masahiko shimizu

TI__Intellectual 1680 points

Hi Shimizu,

You can use smaller paper if you make sure that it occupies major part of the FoV. Please make sure that none of the pixels are saturated also.

Regards

Nithin

0 LeonardEllis over 8 years ago in reply to Nithin Jose

TI__Guru 71516 points

Nithin,

In the VoxelViewer User Guide http://www.ti.com/lit/ug/sbou157/sbou157.pdf , it says to "contact TI for the checkerboard pattern" so I assume this means to obtain a file that can be printed. Where is the file available? If not on the website, how does a customer request this file?

~Leonard

0 Nithin Jose over 8 years ago in reply to LeonardEllis

TI__Intellectual 1680 points

Leonard,
I have attached a reference checkerboard in this same thread. As I have already mentioned, we recommend using a checker board with odd no. of squares in one direction and even no. of squares in the other direction. There is no hard requirement on the dimensions of the squares. When you are using checker board for calibration, kindly make sure it occupies major part of the FoV.

Thanks
Nithin

0 Jorick Astrego over 7 years ago in reply to Nithin Jose

Intellectual 760 points

Tip for anyone looking for a calibration pattern, OpenCV has a tool to generate them:

https://github.com/opencv/opencv/blob/master/doc/pattern_tools/gen_pattern.py

Usage example:
python gen_pattern.py -o out.svg -r 11 -c 8 -T circles -s 20.0 -R 5.0 -u mm -w 216 -h 279
-o, --output - output file (default out.svg)
-r, --rows - pattern rows (default 11)
-c, --columns - pattern columns (default 8)
-T, --type - type of pattern, circles, acircles, checkerboard (default circles)
-s, --square_size - size of squares in pattern (default 20.0)
-R, --radius_rate - circles_radius = square_size/radius_rate (default 5.0)
-u, --units - mm, inches, px, m (default mm)
-w, --page_width - page width in units (default 216)
-h, --page_height - page height in units (default 279)
-a, --page_size - page size (default A4), supercedes -h -w arguments
-H, --help - show help

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Voxel Viewer About checkerboard pattern