Comments on: Glossary of the Gameday pitch fields http://fastballs.wordpress.com/2007/08/02/glossary-of-the-gameday-pitch-fields/ Musings on baseball Wed, 04 Nov 2009 18:01:08 +0000 http://wordpress.com/ hourly 1 By: Back to the Grind « The Mockingbird http://fastballs.wordpress.com/2007/08/02/glossary-of-the-gameday-pitch-fields/#comment-487 Back to the Grind « The Mockingbird Thu, 03 Jul 2008 18:00:36 +0000 http://fastballs.wordpress.com/2007/08/02/glossary-of-the-gameday-pitch-fields/#comment-487 [...] the string that attaches both ends and the middle of the bow (here’s a graphic stolen from Mike Fast, who adapted it from Mike [...] [...] the string that attaches both ends and the middle of the bow (here’s a graphic stolen from Mike Fast, who adapted it from Mike [...]

]]> By: Mike Fast http://fastballs.wordpress.com/2007/08/02/glossary-of-the-gameday-pitch-fields/#comment-201 Mike Fast Sun, 25 Nov 2007 19:44:04 +0000 http://fastballs.wordpress.com/2007/08/02/glossary-of-the-gameday-pitch-fields/#comment-201 Flip, thanks for the link to your drawing. I can't see anything in the PDF file, and I don't have Mathematica, so I can't see your calculations. The calculations all worked out for me to replicate the pfx_x and pfx_z numbers from the other PITCHf/x data when they were calculated at y=1.417 feet. However, you have to include the effect of drag, i.e., the y acceleration. Flip, thanks for the link to your drawing.

I can’t see anything in the PDF file, and I don’t have Mathematica, so I can’t see your calculations.

The calculations all worked out for me to replicate the pfx_x and pfx_z numbers from the other PITCHf/x data when they were calculated at y=1.417 feet. However, you have to include the effect of drag, i.e., the y acceleration.

]]> By: mrflip http://fastballs.wordpress.com/2007/08/02/glossary-of-the-gameday-pitch-fields/#comment-200 mrflip Sun, 25 Nov 2007 15:38:37 +0000 http://fastballs.wordpress.com/2007/08/02/glossary-of-the-gameday-pitch-fields/#comment-200 I made a <a href="http://vizsage.com/apps/baseball/results/pitchfx" rel="nofollow">drawing illustrating the trajectories and the various data fields</a> with Sketchup (Google's free 3-d program) (<a href="http://vizsage.com/apps/baseball/results/pitchfx/PitchFXDiagram.png" rel="nofollow">PNG preview</a>). It's free for all to use as they please. I believe that the pfx_x and pfx_z offset endpoints are not at the strike zone plane (y=1.417ft) but rather at the dragless ball's position when the actual pitch crosses the strike plane. (That is, their positions at the same *time*, not the same *final y* value). The ending y position for the dragless path is somewhere near or even behind home plate: if you parameterize by y you have to find the dragless ball's terminal position from the actual pitch's strikezone-crossing time. I left a <a href="http://vizsage.com/apps/baseball/results/pitchfx/PitchFX-calcs.nb" rel="nofollow">messy mathematica notebook</a> (<a href="http://vizsage.com/apps/baseball/results/pitchfx/PitchFX-calcs.pdf" rel="nofollow">PDF</a>) with my calculations up there, if that's useful. This, at least, made my calculations come out to agree with the data files where nothing else would. I made a drawing illustrating the trajectories and the various data fields with Sketchup (Google’s free 3-d program) (PNG preview). It’s free for all to use as they please.

I believe that the pfx_x and pfx_z offset endpoints are not at the strike zone plane (y=1.417ft) but rather at the dragless ball’s position when the actual pitch crosses the strike plane. (That is, their positions at the same *time*, not the same *final y* value). The ending y position for the dragless path is somewhere near or even behind home plate: if you parameterize by y you have to find the dragless ball’s terminal position from the actual pitch’s strikezone-crossing time. I left a messy mathematica notebook (PDF) with my calculations up there, if that’s useful. This, at least, made my calculations come out to agree with the data files where nothing else would.

]]> By: Alan Nathan http://fastballs.wordpress.com/2007/08/02/glossary-of-the-gameday-pitch-fields/#comment-11 Alan Nathan Tue, 07 Aug 2007 21:30:44 +0000 http://fastballs.wordpress.com/2007/08/02/glossary-of-the-gameday-pitch-fields/#comment-11 Thanks for the plug about the glossary. I have just written a brief article that is in the "nearly ready for prime time" category. You can download this article at http://webusers.npl.uiuc.edu/~a-nathan/pob/Analysis.pdf Before I go public with it, I would appreciate comments from any of you who are interested. Thanks for the plug about the glossary. I have just written a brief article that is in the “nearly ready for prime time” category. You can download this article at
http://webusers.npl.uiuc.edu/~a-nathan/pob/Analysis.pdf Before I go public with it, I would appreciate comments from any of you who are interested.

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