Finding area of racquet head

Radicalized

Professional
url=https://ibb.co/Bt88NhT]
inkscape-racquet.jpg
[/url]
Finding the Area Inside a Tennis Racquet Frame

I was working with the software mentioned below and decided to post this. A TT member may want to find the area of some racquet head, old or maybe even new. So here it is if it's ever of any use.

First, I'm not using a photo of the racquet because of more error because of the the camera position. Also, when imported, the size of the image will likely not be correct and would have to be exactly scaled beforehand in a photo editor. I'm not going into the details how to measure in the software and scale to correct.

Note: I posted something like this is the past in some thread, but I didn't give specfic details. Also, then I used a more tedious method where I converted a file into a .dxf file for CAD and did the work there after a number of necessary modifications.

This requires the following:

2 sheets of paper--colored is better unless you color (define) the edges before scanning (string bed is too large and the scanner bed most likely isn't large enough to do with one piece)
Pencil or pen, etc.
Scissors
Computer
Free: Inkscape open-source vector graphics software
Scanner

Note: These are the basics. I'm not getting into extra details about paths and nodes or other aspects of the software. It's minimal steps for most situations. It's quicker and easier than the text seems to present it.

1. Trace the shape inside the frame on the sheets of paper. Cut them out (a top section and bottom section). Lay them on top of the strings if strung to be sure the whole area is covered with no overlap.
2. Draw a square on each paper section, such as 2" x 2" or 3" x 3". This will let you check a known area in the software later as confirmation.
3. Scan each section with your standard scanning software. A common JPEG works. 300dpi is a good enough resolution to work with when defining the borders in the software.
4. In Inkscape (installed like common software): File>Import. Locate and choose a section that was scanned. Pop-up image import: Select the following: Embed, From file, and any rendering mode. OK.
5. The image appears on the workspace. File>Document Properties. Then make display units in inches. Close the Document Properties window.
6. Use scroll bars and zoom to display the square so it is large enough to work with. On the left in the toolbox, click the "Draw Bezier Curves and Staightlines." It resembles a blue tipped pen. It is above the yellow "pencil."
7. With the "Draw" tool just selected you'll see "Mode" at the top-left. Click on the first "Create regular Bezier path" or "Create a sequence of straight lines." Both will work for this.
8. Click a corner of the square to set a node. Go around clicking each corner. When you return to the first node set, it will turn red with the pointer on it. Click again. There is now a path around the square you drew (dotted line shown). The square is still selected.
Optional: You can select and see the nodes of the path around of the square by selecting the "Edit paths by nodes" tool (triangle with with three dots) at the left in the toolbox.
9. Now to find the area.
The square should still be selected. On the menu bar, click "Extensions." Then click Visualize Path>Measure Path. In the window that appears, change the measurement type to "Area." The font size and other options below determine how and where the area text appears relative to the square. Make the text larger to make it more visible. Set the length unit to inches. Click Apply. The software will perform the calculation. If it gives an error, make sure the path of the square is selected as noted above. Click on the work area or close the Measure window. You should see the area of the square displayed, such as 9 sq. in. for the 3" square (image size will provide acccurate results with imported image). There is likely to be a discrepancy, such as 9.03 or something, even if you drew the square well in the first place. That's just a matter of the manual precision.

Now, just repeat the process. This time, after selecting the "Draw Bezier Curves and Staightlines" tool, carefully click around on the outside of the racquet section, completing it as accurately as possible. Zoom in and use the scrolls bars to work your way around. You're performing the same process but instead of four lines, it's more clicks to create more nodes for the path around the racquet section. Use the area function noted above when the path is completed. Then do the same thing for the other racquet section. Add the sections together for the total.
 
Last edited:

FranzS

Semi-Pro
Or... take a middle cross string as your 'zero-line' (x axis) and take the origin reference point where it meets the hoop leftwards, then for each main string measure its x position and its the lenght from the 'zero-line' cross string to where it meets the upper hoop (y position).
Perform multi-linear regression from the set of all (x,y) points you collected to find the best polynomial of chosen degree that best interpolates them (I guess a fourth degree polynomial will suffice considering a typical hoop shape with its couple of curvature radii).
Calculate the integral of that polynomial from x = 0 to x = [length of the reference cross string] and that's the area of the upper hoop.
Repeat for area of lower hoop.
;)
 
Or... take a middle cross string as your 'zero-line' (x axis) and take the origin reference point where it meets the hoop leftwards, then for each main string measure its x position and its the lenght from the 'zero-line' cross string to where it meets the upper hoop (y position).
Perform multi-linear regression from the set of all (x,y) points you collected to find the best polynomial of chosen degree that best interpolates them (I guess a fourth degree polynomial will suffice considering a typical hoop shape with its couple of curvature radii).
Calculate the integral of that polynomial from x = 0 to x = [length of the reference cross string] and that's the area of the upper hoop.
Repeat for area of lower hoop.
;)
This is triggering for me.
 

Mr.Lob

G.O.A.T.
url=https://ibb.co/Bt88NhT]
inkscape-racquet.jpg
[/url]
Finding the Area Inside a Tennis Racquet Frame

I was working with the software mentioned below and decided to post this. A TT member may want to find the area of some racquet head, old or maybe even new. So here it is if it's ever of any use.

First, I'm not using a photo of the racquet because of more error because of the the camera position. Also, when imported, the size of the image will likely not be correct and would have to be exactly scaled beforehand in a photo editor. I'm not going into the details how to measure in the software and scale to correct.

Note: I posted something like this is the past in some thread, but I didn't give specfic details. Also, then I used a more tedious method where I converted a file into a .dxf file for CAD and did the work there after a number of necessary modifications.

This requires the following:

2 sheets of paper--colored is better unless you color (define) the edges before scanning (string bed is too large and the scanner bed most likely isn't large enough to do with one piece)
Pencil or pen, etc.
Scissors
Computer
Free: Inkscape open-source vector graphics software
Scanner

Note: These are the basics. I'm not getting into extra details about paths and nodes or other aspects of the software. It's minimal steps for most situations. It's quicker and easier than the text seems to present it.

1. Trace the shape inside the frame on the sheets of paper. Cut them out (a top section and bottom section). Lay them on top of the strings if strung to be sure the whole area is covered with no overlap.
2. Draw a square on each paper section, such as 2" x 2" or 3" x 3". This will let you check a known area in the software later as confirmation.
3. Scan each section with your standard scanning software. A common JPEG works. 300dpi is a good enough resolution to work with when defining the borders in the software.
4. In Inkscape (installed like common software): File>Import. Locate and choose a section that was scanned. Pop-up image import: Select the following: Embed, From file, and any rendering mode. OK.
5. The image appears on the workspace. File>Document Properties. Then make display units in inches. Close the Document Properties window.
6. Use scroll bars and zoom to display the square so it is large enough to work with. On the left in the toolbox, click the "Draw Bezier Curves and Staightlines." It resembles a blue tipped pen. It is above the yellow "pencil."
7. With the "Draw" tool just selected you'll see "Mode" at the top-left. Click on the first "Create regular Bezier path" or "Create a sequence of straight lines." Both will work for this.
8. Click a corner of the square to set a node. Go around clicking each corner. When you return to the first node set, it will turn red with the pointer on it. Click again. There is now a path around the square you drew (dotted line shown). The square is still selected.
Optional: You can select and see the nodes of the path around of the square by selecting the "Edit paths by nodes" tool (triangle with with three dots) at the left in the toolbox.
9. Now to find the area.
The square should still be selected. On the menu bar, click "Extensions." Then click Visualize Path>Measure Path. In the window that appears, change the measurement type to "Area." The font size and other options below determine how and where the area text appears relative to the square. Make the text larger to make it more visible. Set the length unit to inches. Click Apply. The software will perform the calculation. If it gives an error, make sure the path of the square is selected as noted above. Click on the work area or close the Measure window. You should see the area of the square displayed, such as 9 sq. in. for the 3" square (image size will provide acccurate results with imported image). There is likely to be a discrepancy, such as 9.03 or something, even if you drew the square well in the first place. That's just a matter of the manual precision.

Now, just repeat the process. This time, after selecting the "Draw Bezier Curves and Staightlines" tool, carefully click around on the outside of the racquet section, completing it as accurately as possible. Zoom in and use the scrolls bars to work your way around. You're performing the same process but instead of four lines, it's more clicks to create more nodes for the path around the racquet section. Use the area function noted above when the path is completed. Then do the same thing for the other racquet section. Add the sections together for the total.

I agree.
 

FranzS

Semi-Pro
Or also, after step 1, cut several sheets of (preferably heavy) paper with the same shape, weigh them using a precisione scale, divide total weight by the specific area weight (g/cm2) of the paper
 

BlueB

Legend
Very usefull for odd shaped racquets like Yonex, etc. For classical shaped oval racquets it's close enough to add long and short axis and divide by 4, then use that as radius in the normal formula for circle area.
 

penguin

Professional
url=https://ibb.co/Bt88NhT]
inkscape-racquet.jpg
[/url]
Finding the Area Inside a Tennis Racquet Frame

I was working with the software mentioned below and decided to post this. A TT member may want to find the area of some racquet head, old or maybe even new. So here it is if it's ever of any use.

First, I'm not using a photo of the racquet because of more error because of the the camera position. Also, when imported, the size of the image will likely not be correct and would have to be exactly scaled beforehand in a photo editor. I'm not going into the details how to measure in the software and scale to correct.

Note: I posted something like this is the past in some thread, but I didn't give specfic details. Also, then I used a more tedious method where I converted a file into a .dxf file for CAD and did the work there after a number of necessary modifications.

This requires the following:

2 sheets of paper--colored is better unless you color (define) the edges before scanning (string bed is too large and the scanner bed most likely isn't large enough to do with one piece)
Pencil or pen, etc.
Scissors
Computer
Free: Inkscape open-source vector graphics software
Scanner

Note: These are the basics. I'm not getting into extra details about paths and nodes or other aspects of the software. It's minimal steps for most situations. It's quicker and easier than the text seems to present it.

1. Trace the shape inside the frame on the sheets of paper. Cut them out (a top section and bottom section). Lay them on top of the strings if strung to be sure the whole area is covered with no overlap.
2. Draw a square on each paper section, such as 2" x 2" or 3" x 3". This will let you check a known area in the software later as confirmation.
3. Scan each section with your standard scanning software. A common JPEG works. 300dpi is a good enough resolution to work with when defining the borders in the software.
4. In Inkscape (installed like common software): File>Import. Locate and choose a section that was scanned. Pop-up image import: Select the following: Embed, From file, and any rendering mode. OK.
5. The image appears on the workspace. File>Document Properties. Then make display units in inches. Close the Document Properties window.
6. Use scroll bars and zoom to display the square so it is large enough to work with. On the left in the toolbox, click the "Draw Bezier Curves and Staightlines." It resembles a blue tipped pen. It is above the yellow "pencil."
7. With the "Draw" tool just selected you'll see "Mode" at the top-left. Click on the first "Create regular Bezier path" or "Create a sequence of straight lines." Both will work for this.
8. Click a corner of the square to set a node. Go around clicking each corner. When you return to the first node set, it will turn red with the pointer on it. Click again. There is now a path around the square you drew (dotted line shown). The square is still selected.
Optional: You can select and see the nodes of the path around of the square by selecting the "Edit paths by nodes" tool (triangle with with three dots) at the left in the toolbox.
9. Now to find the area.
The square should still be selected. On the menu bar, click "Extensions." Then click Visualize Path>Measure Path. In the window that appears, change the measurement type to "Area." The font size and other options below determine how and where the area text appears relative to the square. Make the text larger to make it more visible. Set the length unit to inches. Click Apply. The software will perform the calculation. If it gives an error, make sure the path of the square is selected as noted above. Click on the work area or close the Measure window. You should see the area of the square displayed, such as 9 sq. in. for the 3" square (image size will provide acccurate results with imported image). There is likely to be a discrepancy, such as 9.03 or something, even if you drew the square well in the first place. That's just a matter of the manual precision.

Now, just repeat the process. This time, after selecting the "Draw Bezier Curves and Staightlines" tool, carefully click around on the outside of the racquet section, completing it as accurately as possible. Zoom in and use the scrolls bars to work your way around. You're performing the same process but instead of four lines, it's more clicks to create more nodes for the path around the racquet section. Use the area function noted above when the path is completed. Then do the same thing for the other racquet section. Add the sections together for the total.
Can't you do it off the photos on the tw website using the length of the racquet to get scale?
 

Radicalized

Professional
Can't you do it off the photos on the tw website using the length of the racquet to get scale?
I've thought of that. The issue is the image must be scaled perfectly to its actual size in the software. It's no problem for me to do the math and then use the scaling/resolution/resizing functions. However, there needs to be something in the image on the racquet, let's say, to use as a reference. Without getting specific, think of forensic rulers used for archeology or crime scene photos. I wouldn't want to just say, I'll resize to make it 26" long and everything else will fall into place. I could do that easily, but the accuracy would be in question. Second, I like to make a template that fits perfectly on the stringbed, for example. Then the thin layer sits perfectly flat on the scanner glass. Third, there is the issue of any distortion caused by the camera. It's more an issue of precision.

Technically, members could make templates of their own racquets, scan them, and then post them. But as I've said, I'm not up for a full on project.
 

Radicalized

Professional
Can't you do it off the photos on the tw website using the length of the racquet to get scale?
I don't know your background so I'm just going to point out what may be obvious.

The reason I used that software is that it is free, open-source, and easy to use. So, any member could try it. If you want to try it with the photos, save one from the site. Crop it top and bottom. Resize it as necessary. Save. Use the directions above.

Of course, some members may have access to expensive CAD software or Adobe products. But for everyone, there are FOSS options. Various types of software are available with these functions.

If someone needs an image editor, download GIMP from the official site.
 

Radicalized

Professional
Would be interesting to try this Area Calculator application. It says it can measure area of irregular shapes ...





Probably works great. You have to "sign up" as with all of their products now. Then after the trial period, however long that lasts, you pay at least a 24 hour usage fee of $2.49, assuming you can do all the work in one day. 11.99 monthly.

It's the same idea. You just need an accurate image to draw around the required area of interest. They just have automated output for specific needs, such as a surveyor.
 
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