I see. The shot in the diagram is less than 90 degrees so it should still be possible just difficult without masse. But throw will effect it though. If I am looking at this correctly then the cut angle is changing as the cue ball moves along the blue line. It is a different shot completely by the time it gets within 4" of the object ball. Thanks for the clarification
Billiard Architect: Finding the impossible shot
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I see. The shot in the diagram is less than 90 degrees so it should still be possible just difficult without masse. But throw will effect it though. If I am looking at this correctly then the cut angle is changing as the cue ball moves along the blue line. It is a different shot completely by the time it gets within 4" of the object ball. Thanks for the clarification
Ok here is a better graphic of why a 70 degree shot cannot be made from 4 inches away. The red ball is the object ball. The black ball is the cueball and the blue ball is the location that the cueball must contact the red object ball to cut it 70 degrees. If you were to shoot this this shot, the balls would collide at the green dot on the edge of the red object ball sending it at a 40 degree angle from the cueball and object ball center line.
As you can see you cannot execute a true 70 degree cut from 4 inches away.
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Snipped for sanity.
Your graph basically shows that ghost ball works, and that if you attempt to line up a shot by using the centers of the CB and OB you will become confused. So, moral of this story, don't set up the problem in that way.
That's not what he's saying.
The confusion arises because there are two different angles which need to be distinguished with two different names. Using his original diagram, the "cut angle" is the angle between the black line (desired OB direction) and the CB's direction (either the red or yellow line). The "impact angle" (Dr. Dave's term) is the angle between the black line (OB's direction) and the blue line (line of centers direction).
The 'cut angle' can always be from 0 to 90 degrees, but the maximum 'impact angle' will always be less than 90 degrees unless the balls are an infinite distance apart.
You can also define the "approach angle" or "ghostball angle" (Dr. Dave's term) as the angle between the blue line (line of centers) and the CB's direction (either the red or yellow). Then the cut angle is equal to the sum of the approach and impact angles. Or, maybe more to the point, the impact angle is equal to the cut angle minus the approach angle. Thus, for the same contact point, the maximum impact angle decreases as the balls are moved closer together along their line of centers, because the approach angle increases while the maximum cut angle remains fixed at 90 degrees (ignoring throw).
More succinctly, in the diagram below, Angle C = Angle G + Angle P (cut angle = approach angle + impact angle),
and therefore Angle P = Angle C - Angle G.
Jim
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The confusion is in the assumed cut angle. The shot hes calling a 70* cut , most everyone else would consider to be in actuality a 110* cut (or thereabouts) .
His explanation of the angle of the cut as the CB approaches the OB is another place where hes going wrong.
If he was closing the gap between the OB and CB on the correct line, he would find out the the cut angle never changes all the way up untill the 2 balls touch. AKA the ghost ball position.
Obviously you can cut a ball all the way up to 90* (and actually a hair beyond) regardles of the distance between the 2 balls.
His explanation of the angle of the cut as the CB approaches the OB is another place where hes going wrong.
If he was closing the gap between the OB and CB on the correct line, he would find out the the cut angle never changes all the way up untill the 2 balls touch. AKA the ghost ball position.
Obviously you can cut a ball all the way up to 90* (and actually a hair beyond) regardles of the distance between the 2 balls.
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AFAIK nobody indicates the angle of the shot through the centers of the CB/OB, that is just confusing. Use the line through the GB/OB, and line through CB/GB. There is your angle. In this diagram where you indicate a 70 degree cut is actually beyond 90 degrees. Anything beyond 90 will require spin, masse or a kick
I understand what he's trying to do now that I looked at the tutorial for his app.
http://www.youtube.com/watch?v=XMuuWSHWWe4
You place the phone over the object ball, input the distance to the QB, point the "cursor" back to the center of the cue ball, then get the angle/overlap from the program.
Using this method, the angle does change since it's not based on the aiming line to begin with. Might be useful for a beginner to start learning angles.
http://www.youtube.com/watch?v=XMuuWSHWWe4
You place the phone over the object ball, input the distance to the QB, point the "cursor" back to the center of the cue ball, then get the angle/overlap from the program.
Using this method, the angle does change since it's not based on the aiming line to begin with. Might be useful for a beginner to start learning angles.
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I am dealing in concrete lines here. The CB to OB center line never changes over distance where as the ESTIMATED (or better terms GUESSED, SHOT IN THE DARK, FUZZY I THINK SO CUZ THAT IS THE WAY I HAVE EXPERIENCED IT IN THE PAST) line needs to change as you get closer or further away from the ball. When calculating a shot I would much rather have a constant.
That is good, objective lines for aiming. However, you still need to find that fuzzy guess shot line from the CB-OB center, don't you? The aim angle changes for all distances from CB-OB, not just within 4 inches.
I usually stay out of type thing,,but what I see as obvious here. Is if your to make a comparison of moving the cue closer. It should be moved on the same line as to make the shot. NOT the bee line between the 2 balls.
How can you make this comparison if leaving the travel path that makes the ball??
It makes no sense to me at all,,it means nothing. Just setting up a different shot.
It's kinda like saying if I move the cue over here behind this ball,,,blocking the shot on the OB,,,and saying,,look the shot cannot be made now. LOL
How can you make this comparison if leaving the travel path that makes the ball??
It makes no sense to me at all,,it means nothing. Just setting up a different shot.
It's kinda like saying if I move the cue over here behind this ball,,,blocking the shot on the OB,,,and saying,,look the shot cannot be made now. LOL
I can line my cue up with the OB to CB center line on any shot and it is in the same location for RH or LH or 10 degree, 20 degree, 37.26 degree cuts or any cut.
Trying to guess where Ghost Ball line is only just that... a guess, unless you are allowed to draw a chalk mark on the table exactly 2 1/4 inches from the edge of the object ball in line with the desired object ball path.
I am using the same line. Not a guestimated line based on ghost ball. It is the same shot just the balls are closer to each other. Not along the shot path but physically closer together based on the same cut angle.
No your not.
When you put the cue ball 12" from the object ball, the cue ball is ON THE LINE.
When you put the cue ball 4" from the object ball, the cue ball is NEXT TO THE LINE. Therefore changing the original shot.
Same angle = Doesn't matter the distance.
This is what I get from all this.
Either that or your talking about something that is far beyond my physics.....:shrug:
On any shot, if you observe from the cue-ball just a nano-second before
it strikes the object-ball, you could hit it straight on or cut it 90 degrees
either direction and ( barring throw factor) the object-ball will go into the
pocket.
I'm just not sure what this has to do with knocking the ball in, running out,
and taking your opponent's watch.
it strikes the object-ball, you could hit it straight on or cut it 90 degrees
either direction and ( barring throw factor) the object-ball will go into the
pocket.
I'm just not sure what this has to do with knocking the ball in, running out,
and taking your opponent's watch.
Yes the line through the CB/OB centers is objective and the same, no question there. However, unless the shot is straight in you cannot pocket the ball from that line. You have to adjust your aim to another line, a line that goes through the GB center. Therefore, there is still the same guesswork to find the line of aim.
In answering a related email I realized something... I think we are trying to make a point about 2 different things. You all are seeing my application as an aiming system and I am trying to defend how the application works. How my application calculates the ball to ball overlap is in no means an aiming system. It is just how it gathers information and shows accurately what the aim is by using ball to ball overlap. I believe I put too much information in the video. What I should have showed was inputting the distance, lining up the green dot over the object ball, pointing the line back to the center of the cueball, show the overlap then make the shot aiming at that overlap. Then do the same thing for a different angle etc.
Its like google explaining how chrome displays a web page instead of just doing a promo video.
They don't look the same to me. I'm confused
Bizarre thread...really bizarre.
I'm really confused.
Someone help.
:scratchhead:
I'm really confused.
Someone help.
:scratchhead:
Sure. If the cue ball is shot towards the ghost ball and arrives correctly in the ghost ball position, the shot will go in. The only wrinkle is that you have to modify the ghost ball position a little from the simple position to account for whatever throw there will be on the shot. Any system or drawing that implies anything else is wrong and is best ignored.