Aparallel CTCP aiming method

[Mikjary]

Mike,
I understand and agree with your observations, sources and descriptions.

That one doesn't have to shift from the obverse CP (90) on the OB to the obverse CP (90) on the CB and just pivot is elegant, but it doesn't account for distance of the bridge to the CB, as you said earlier (I believe), when the separation between the OB and CB changes.

I contend that the shift that the "aparallel shift" CTCP that I described at post #1 to the center of the smaller appearing OB does this - compensates for the OB being further down table.

If one can master that shift, it may help one learn to pocket balls - if other methods are not yet mastered.

Thanks again for your input.

LAMas,

You are right about perspective. As the CB/OB distance grows the OB size shrinks. Your diagram noting the aparallel offset is why 90/90 works. The aiming point is on the edge to edge which is not truly a parallel line and it doesn't use a parallel offset.

You adjust using the 3 different 90 positions as the distances change. You don't need to know the OB contact point except to possibly estimate the angle. After you pivot you can see if you're close. If not, use the next 90 setup.

At 8-9 feet away you'll have a short pivot to center because of the aparallel lines, but it is still the same pivot. I use a hip pivot which is more consistent.

Thanks,
Mike

 

[Jal]

...
I contend that the shift that the "aparallel shift" CTCP that I described at post #1 to the center of the smaller appearing OB does this - compensates for the OB being further down table.

LAmas,

I'm still not sure what you mean by an "aparallel shift." Are you saying that if you do a parallel shift by x inches with respect to the table and cueball (move the tip and butt the same amount sideways over the cloth) that you will, in effect, sweep across more of the OB than x inches because of its smaller apparent diameter?

Jim

 

[LAMas]

LAmas,

I'm still not sure what you mean by an "aparallel shift." Are you saying that if you do a parallel shift by x inches with respect to the table and cueball (move the tip and butt the same amount sideways over the cloth) that you will, in effect, sweep across more of the OB than x inches because of its smaller apparent diameter?

Jim

I think that your question is correct if I interpret what you ask is correct sir.

When I started to read about CTE, I interpreted a parallel shift as described by some posters, blogs and websites as a proportional shift from the top view of the table - CTE would be aiming the tip of my cue at the center of the CB to the edge of the OB.

The next instruction was to shift the cue one cue tip diameter by some and 1/2 ball by other/s. If I discuss the 1/2 ball shift, then, I would shift my aim from CTE to the center of the OB (1/2 ball) to the edge of the CB (1/2 ball) - this would be correct and parallel from the top view.

As you ask, when down on the shot, the parallel shift (like rolling a dowel) of 1/2 ball at the smaller apearing OB would not traverse the same distance across the CB - this is counter intuative but real - see post #1 that I proffer.

Further, I have drawn in Acad (2D CAD drawing tool) Aparallel CTCP (which it is geometrically correct) and it documents:

- The eye is a single point that recieves light rays from ~180 degress
so that object close to the eye appear larger than those further away.

- The CB will always appear larger than the OB.

- That there is a linear relationship of the appearant decreasing diameter of the OB as it is moved further away from the eye.

- Assume that the bridge is one foot away from the eye, the CB is one foot away from the bridge, then Aparallel CTCP will not require the moving of the bridge for different distances between the CB and OB for all cut angles. The geometric relationship is linear.

Thanks for your interest.

 

[Jal]

....
As you ask, when down on the shot, the parallel shift (like rolling a dowel) of 1/2 ball at the smaller apearing OB would not traverse the same distance across the CB - this is counter intuative but real - see post #1 that I proffer.

Further, I have drawn in Acad (2D CAD drawing tool) Aparallel CTCP (which it is geometrically correct) and it documents:

It's the rolling a dowel analogy that has me questioning what you mean by "aparallel." It implies that you're doing a true parallel shift (moving the tip and butt by the same amount sideways across the cloth). If so, you will in fact move the same distance across the OB.

I think this is clear from the following diagrams. The first is a top view showing two parallel lines 1/2 ball apart. Imagine doing a parallel shift (rolling a dowel) by that much.



Here's the same diagram, untouched and unadulterated, from the shooters perspective, more or less. This was accomplished not by redrawing the picture, but simply changing the view (more on that in a moment).



Since you've obviously put a lot of work into your diagrams, but can't do perspective projections with your current software, you might be interested in Google's SKetchup. A poster here, Slide Rule, alerted me to it and I've been going through the tutorial videos over the weekend (being on dialup, it takes time). It's a pretty sophisticated program and amazing that you can get it for free. If you're interested, here are some links:

http://sketchup.google.com/training/

http://sketchup.google.com/training/videos/new_to_gsu.html


Here's an example of a masse gone wrong.

That there is a linear relationship of the appearant decreasing diameter of the OB as it is moved further away from the eye.

Generally speaking, if you include objects that are large and close (i.e., subtend large angles) it's not a linear decrease in size with distance. But for balls on a pool table, unless your eye is really close to the CB, for instance, I agree with your statement as a practical matter. (Apparent size varies with distance as the tangent, a trig function, of the subtended angle, which is nearly linear at small angles.)

Just discussing.

Jim

 

[Dave Nelson]

Some posts and threads are difficult enough((damned hard, impossible(for me) )) without the necessity
for horizontal scrolling.

Dave Nelson

 

[Dead Crab]

One way to deal with the OB distance-perspective debacle is to ignore it.

You can do this because there is no information on the OB that is not also (and usually more easily) identifiable on the CB.

Read above sentence again. It is true.

So, if you can identify the location of the contact point on the OB, you can find the analogous point on the CB. Note this is the basis of parallel line systems.

Since you are close to the CB, you can make a good estimate of the center to contact point distance. If you want to double the distance, do so, and you then have the aim-point distance.

Place your cue on the line connecting a point on the CB EQUAL to the aim point distance, on the OPPOSITE side of the CB, to the center of the OB. Then parallel shift back to the center of the CB. You now have a line connecting the center of the CB with the aim point on the OB. Pull the trigger.

Example 1: 15 degree cut to left
a) contact point is 7.5 mm to right of center, find this on CB
b) aim point will be 15 mm off center
c) identify point 15 mm to left side of CB (your 13mm tip will allow you to estimate this)
d) align stick thru this point to center of OB
e) parallel shift back to center of CB
f) shoot

If you know how to estimate distances, and the difference between say 20 and 22 mm on a pool ball is something you can deal with, AND if you really want to be married to double-the-distance, then this method may be what you are looking for.

 

[Mikjary]

Some posts and threads are difficult enough((damned hard, impossible(for me) )) without the necessity
for horizontal scrolling.

Dave Nelson

Dave,

LOL! I hate it, too. Go to "view" on your menu toolbar and "zoom". Click on 75% or 50% and you can shrink the screen. The writing will also be smaller, but you can see the diagrams better. It's a tossup. :wink:

Mike

 

[336Robin]

Parallax

Yeah my head hurts a little after seeing some of that but:

It appears you are attempting to make an adjustment for the Parallax on the shot.

Look up the Wikipedia explanation of it and read it. I think you will be surprised at what you find out and simply learn to adjust for.

336robin

aimisthegameinpool@yahoo.com

hit me an email to get on the list for when the cd is ready:thumbup:

 

[LAMas]

Jal,
I can draw in perspective/isometric in ACAD as well later.
For now, I would like to use your perspective/iso with the single vanishing point picture that you are comfortable with.

If you can delete the larger CB nearest you and draw a parallel line to the (angled) line that touches the right side of the OB (and touches the right side of the CB that I asked to be deleted) from the center of the smalller OB, then that is what I am describing as "aparallel" (for it isn't truely parallel if viewed from above).

See the middle example of the drawing in my post #1 in this thread - it's also in perspective.

Notice that the new line will be to the right of the center of the CB - if you superimpose/replace the CB image back in.



Thanks for the pictures.

 

[LAMas]

Yeah my head hurts a little after seeing some of that but:

It appears you are attempting to make an adjustment for the Parallax on the shot.

Look up the Wikipedia explanation of it and read it. I think you will be surprised at what you find out and simply learn to adjust for.

336robin

aimisthegameinpool@yahoo.com

hit me an email to get on the list for when the cd is ready:thumbup:

366,
Thanks, but though I worked with parallax problems with ancient Nixie tube displays years ago, I am not going to go there for I am only talking about a cyclopsian view (one eye above the cue).

If I might rephrase my position, while down on the shot, line the cue up to touch a line from the ,say, right side of the CB to the right side of the OB down at the other end of the table.

Now with your third hand, move the CB to the side and out of the field of view leaving the cue in the original postion.

Now shift the cue to the left, like rolling a dowel, until the cue is now aimed at the center of the OB.

With your third hand, roll the CB back into place and you will notice that the tip of you cue isn't at the center of the CB but is instead to the right of the center of the CB.

As you move the OB closer, and it appears larger, to the CB, your cue tip will be moved closer to the center of the CB. Your shift will move farther to the left away from the the original line.

As the shift is completed/effected, the bridge hand is shifted to the correct postion for the distance between the OB and CB prior to the pivot back to the center of the CB - then shoot.

Thanks for your interest.

 

[Craig Fales]

Just put it in the freakin' hole.

 

[Jal]

Some posts and threads are difficult enough((damned hard, impossible(for me) )) without the necessity
for horizontal scrolling.

Dave Nelson

I don't have to scroll on my computer, but the screen resolution is set at 1024x768. In the future, I'll try to limit widths to account for 800x600.

Jim

 

[LAMas]

One way to deal with the OB distance-perspective debacle is to ignore it.

You can do this because there is no information on the OB that is not also (and usually more easily) identifiable on the CB.

Read above sentence again. It is true.

So, if you can identify the location of the contact point on the OB, you can find the analogous point on the CB. Note this is the basis of parallel line systems.

Since you are close to the CB, you can make a good estimate of the center to contact point distance. If you want to double the distance, do so, and you then have the aim-point distance.

Place your cue on the line connecting a point on the CB EQUAL to the aim point distance, on the OPPOSITE side of the CB, to the center of the OB. Then parallel shift back to the center of the CB. You now have a line connecting the center of the CB with the aim point on the OB. Pull the trigger.

Example 1: 15 degree cut to left
a) contact point is 7.5 mm to right of center, find this on CB
b) aim point will be 15 mm off center
c) identify point 15 mm to left side of CB (your 13mm tip will allow you to estimate this)
d) align stick thru this point to center of OB
e) parallel shift back to center of CB
f) shoot

If you know how to estimate distances, and the difference between say 20 and 22 mm on a pool ball is something you can deal with, AND if you really want to be married to double-the-distance, then this method may be what you are looking for.

Dead Crab,
You are describing a method similar to 90/90 except that instead of aiming at the same point on the OB as the CB, you are saying to aim at the center of the OB before the pivot.

I will look to see what difference that makes, but that is another varient of 90/90 - to me.

Thanks for the heads up.

 

[LAMas]

Just put it in the freakin' hole.

Yup, we all want to.

 

[Mikjary]

As you move the OB closer, and it appears larger, to the CB, your cue tip will be moved closer to the center of the CB. Your shift will move farther to the left away from the the original line.

As the shift is completed/effected, the bridge hand is shifted to the correct postion for the distance between the OB and CB prior to the pivot back to the center of the CB - then shoot.

LAMas,

When the shift is completed are you ending up at the center of the CB to prove the aparallel perspective? Or are you pointing out that the distance of the tip from the center of the CB is the pre-pivot point?

Mike

 

[Dead Crab]

Dead Crab,
You are describing a method similar to 90/90 except that instead of aiming at the same point on the OB as the CB, you are saying to aim at the center of the OB before the pivot.

I will look to see what difference that makes, but that is another varient of 90/90 - to me.

Thanks for the heads up.

No, there is no pivot involved. If there was a pivot, it wouldn't work.

 

[LAMas]

LAMas,

When the shift is completed are you ending up at the center of the CB to prove the aparallel perspective? Or are you pointing out that the distance of the tip from the center of the CB is the pre-pivot point?

Mike

Mike,

Yes,
I am pointing the center of the CB out to the CP on the small OB and then shifting to it's center without regard for the CB. For an OB down table, the shift is very small,

After the small shift, I then pivot toward the center of the OB and shoot.

Thanks.

 

[Jal]

If you can delete the larger CB nearest you and draw a parallel line to the (angled) line that touches the right side of the OB (and touches the right side of the CB that I asked to be deleted) from the center of the smalller OB, then that is what I am describing as "aparallel" (for it isn't truely parallel if viewed from above).

I thought that's what you meant by "aparallel," but then you go on to say (to 366):

...
If I might rephrase my position, while down on the shot, line the cue up to touch a line from the ,say, right side of the CB to the right side of the OB down at the other end of the table.

Now with your third hand, move the CB to the side and out of the field of view leaving the cue in the original postion.

Now shift the cue to the left, like rolling a dowel, until the cue is now aimed at the center of the OB.

With your third hand, roll the CB back into place and you will notice that the tip of you cue isn't at the center of the CB but is instead to the right of the center of the CB....

The 'rolling dowel' part of this description implies a situation like the one I diagrammed earlier, and will result in the cue back at CB center. In other words, a dowel will produce a true physical parallel shift with respect to the table (cloth). This doesn't jive with your first description above, that being of an apparent parallel shift; that is, one that appears parallel in the image plane, but isn't parallel with respect to the table.

If you do an "aparallel" shift as per your first description, the tip moves more sideways than the butt with respect to the table as you shift over to OB center. In effect, you're pivoting the cue about some point behind the cueball. In order to see this as a "parallel shift" in the image plane, the eye has to be positioned at that point. Determining where that point is, such that the second pivot gets you to GB center (ghostball center), is not so easy... at least according to the math I've done thus far. (It's variable and may not permit an easy construction at the table.)

I'm not trying to shout with the bold lettering, but just trying to emphasize the difference between what you see (image plane) versus what's actually taking place on the table.

Jim

 

[Mikjary]

Mike,

Yes,
I am pointing the center of the CB out to the CP on the small OB and then shifting to it's center without regard for the CB. For an OB down table, the shift is very small,

After the small shift, I then pivot toward the center of the OB and shoot.

Thanks.

Well why didn't you just say that???!!! J/K. The next question is how do you learn to shift the correct x distance? You could use feel, but the pivot flamers would have your head. You could use a headset from a helicopter gunship to super-impose coordinates on the CB/OB or...wait a minute!!!...you already have a product ready to market. IIRC your line of work deals with laser guidance for armament systems. Is this thread a marketing initiative for a new pool aiming gizmo? If it is I will buy the first one!:grin-square:

All kidding aside, with any aiming system you have to be able to repeat the process. What have you done to make this happen?

Best,
Mike

 

[LAMas]

I thought that's what you meant by "aparallel," but then you go on to say (to 366):

The 'rolling dowel' part of this description implies a situation like the one I diagrammed earlier, and will result in the cue back at CB center. In other words, a dowel will produce a true physical parallel shift with respect to the table (cloth). This doesn't jive with your first description above, that being of an apparent parallel shift; that is, one that appears parallel in the image plane, but isn't parallel with respect to the table.

If you do an "aparallel" shift as per your first description, the tip moves more sideways than the butt with respect to the table as you shift over to OB center. In effect, you're pivoting the cue about some point behind the cueball. In order to see this as a "parallel shift" in the image plane, the eye has to be positioned at that point. Determining where that point is, such that the second pivot gets you to GB center (ghostball center), is not so easy... at least according to the math I've done thus far. (It's variable and may not permit an easy construction at the table.)

I'm not trying to shout with the bold lettering, but just trying to emphasize the difference between what you see (image plane) versus what's actually taking place on the table.

Jim

I know what you are sayin, but at the table, if I aim a dowel at the near end of the table (cue) at the right edge of the OB down at the far end of the table, and then roll the dowel to the left until it is aimed at the center of the small appearing OB, Then the amount that I roll the dowel (parallel?) is very small and nowhere close to the center of the CB.

Rolling the dowel is a parallel roll and one would expect that the dowel rolled as described above would now be centered on the CB....But it isn't...go figure...counter intuative...optical illusion?

It works for me though.

Tried it at the table?