double-the-distance aiming method (PIM: Pocket Intersection Method)

[dr_dave]

I was an engineering student at the Colorado School of Mines and we had a new freshman come in that could play pool pretty good, but after watching him a long time I noticed he was missing a lot of shots that he should never miss. So I asked him how he was aiming and he said he aimed the cuestick at the contact point on every shot.

So I told him that it wouldn't work for every shot and that's why he misses some shots consistently.

My conversation with him made me think about HOW to aim the cuestick and how to derive a mathematically correct aim point for every shot.

So using E2 paper I started trying to derive a geometric rule of where to aim the cueball to make every shot. I noticed that if the CB and OB are the same size that the CP (contact point) will always be halfway between the center of the OB and the center of the CB when you flatten it back to two dimensions. So I just went to a pool hall and started measuring and it worked. Small step from there to just visualize the distance from the center-to-center point and double it.

The caveat is that it's dependent on you having good vision AND the position of your dominant eye comes into play. I thought that it would work better if you used your dominant eye to sight down the cue like a rifle. If you played with the cue in between your eyes, I thought the system would break down. I had always played with my dominant eye over my cue so it wasn't a big adjustment for me.

I wasn't looking for it to be a be-all end-all system, I just wanted to be able to create a correct reference point for aiming when my 'feel' wasn't there. Sometimes we have that tough table-length shot for the game and we 'try' harder. I would miss those shots too much. I developed this system specifically to help me in those situations. In those situations, having a repeatable, simple way to get to the correct aim point (without spin) was invaluable. I got the reputation of having ice in my veins because I usually made the tough shot for the cash. My secret was having this system to fall back on. Shoot the shot medium, center ball and bingo. Made some really unbelievable shots for the cash using it.

~rc

Thanks for the background.

Although, I find it hard to believe that a pool-playing engineer would be aiming at the contact point ... engineers are usually better at geometry than that (no offense to JoeW the psychologist :grin-square.

I also like to have a backup plan (e.g., finding the ghost-ball) when a shot doesn't "look right" to my "aiming intuition."

Regards,
Dave

 

[dr_dave]

http://forums.azbilliards.com/showthread.php?t=152631
Tape 1.
Vol 1. Sighting & Aiming
A complete discussion of aiming systems. Including how to aim the cue, the double distance aiming system, the five major hits system, why you miss certain shots, why you rattle the ball in the pocket, and more.

Thanks. Do you know the Copyright year?

Thanks again,
Dave

 

[sixpack]

Thanks for the background.

Although, I find it hard to believe that a pool-playing engineer would be aiming at the contact point ... engineers are usually better at geometry than that (no offense to JoeW the psychologist :grin-square.

I also like to have a backup plan (e.g., finding the ghost-ball) when a shot doesn't "look right" to my "aiming intuition."

Regards,
Dave

Well, he was a Freshman. And I think he transferred to CSU :grin:

~rc

 

[Cornerman]

If you do, please post a link.

I can't find anything. It's odd. I can only say that this is an old system that there has been enough talked about it on the internet that it should be easily found. But there isn't.

If you search this site, you'll even see where I reference several double the distance methods, yet, I can't find any posts!!!

The articles are out there, but possibly in magazines. It might be called Times Two, Equal Distance, Center of Overlap, etc. All the same geometrically correct system.

Fred

 

[Clark_the_Shark]

I think the DIM, Ghost ball, Joe Tucker's, and what I am calling the "Parallel Line Aiming Method" (Described in the book "Precision Pool" with Gerry Kanov & Shari Stauch) and described in fine detail here... http://forums.azbilliards.com/showpost.php?p=230576&postcount=37 are all very similar methods. But personally, for hard to estimate shots, or even combos and easy shots, I feel the "Parallel Line" method and/or Ghost Ball method works the best.

The Parallel line method is EXACTLY like Joe Tucker's aiming method except he uses numbers to identify each spot, whereas you don't need any numbers to memorize with this method.

Very simply, you just take the contact point on the opposite side of the OB (the point CLOSEST to the pocket) and visualize that exact point on the CUE BALL, then drive the point on the cue ball to the contact point on the object ball.

It's explained better in the book with visuals, and the link I provided shows exactly what I am talking about. It looks complicated, but if you just take 1 minute to read it to understand it, it's perfectly clear.

 

[dr_dave]

I can't find anything. It's odd. I can only say that this is an old system that there has been enough talked about it on the internet that it should be easily found. But there isn't.

If you search this site, you'll even see where I reference several double the distance methods, yet, I can't find any posts!!!

The articles are out there, but possibly in magazines. It might be called Times Two, Equal Distance, Center of Overlap, etc. All the same geometrically correct system.

I've seen posts talking about the system where you bisect the distance between the CB and OB, and pivot and shift the cue. I have a quote here:

http://billiards.colostate.edu/threads/aiming.html#bisect​

but the "double the distance" method in this thread is different. And, unfortunately, it really isn't "geometrically correct," because it relies on the "large distance" assumption. But it does work well (theoretically) for most shots.

Thanks again,
Dave

 

[dr_dave]

Well, he was a Freshman. And I think he transferred to CSU :grin:

You must have meant CU. At CSU, we don't accept engineering students with such poor geometry skills.

Regards,
Dave

PS: Do you still ski?

 

[Cornerman]

I've seen posts talking about the system where you bisect the distance between the CB and OB, and pivot and shift the cue. I have a quote here:

http://billiards.colostate.edu/threads/aiming.html#bisect​

but the "double the distance" method in this thread is different. And, unfortunately, it really isn't "geometrically correct," because it relies on the "large distance" assumption. But it does work well (theoretically) for most shots.

Thanks again,
Dave

You're right. As written, this one is different. All of the other Double the Distance, Equal Overlap, etc. systems don't do Step 1.

BTW, that pivot and shift version is not one of the old Double the Distance methods that was discussed. The Preacher article is probably the one older posters are talking about.

Fred

 

[woody_968]

http://forums.azbilliards.com/showthread.php?t=152631
Tape 1.
Vol 1. Sighting & Aiming
A complete discussion of aiming systems. Including how to aim the cue, the double distance aiming system, the five major hits system, why you miss certain shots, why you rattle the ball in the pocket, and more.

Dons delivery in the tapes was a little dry, but IMHO his series had some of the best content of any that I have watched.

I think he also did a good job of explaining the dominant eye and options in how to sight the shot.

 

[Slide Rule]

Minor Error in Double the Distance

I have been working on aiming systems and capturing features of them. The following is what I noted relating to Double the Distance method.

A small grey triangle represents the error. For the red and green triangles to be equal the lines drawn from the cue ball to the centers of the object ball and virtual cue ball at contact would have to be parallel (which they are not). There is a small error inherent to the method. The method may be a good enough as first order approximation for distances sufficiently far from the object ball or for cases where the cut angle is sufficiently small. Note that the diagram shows a relatively severe cut shot. The error may be sufficient to cause a missed shot due to hitting the object ball slightly too full.

Sorry, I can't attach the diagram. Direct me, as to how, if you would like to see it.

Slide Rule

Al

 

[dr_dave]

Dons delivery in the tapes was a little dry, but IMHO his series had some of the best content of any that I have watched.

I think he also did a good job of explaining the dominant eye and options in how to sight the shot.

Could you briefly describe what Don recommends in this regard? It sounds like it might be similar to Gene's PERFECT AIM.

Thanks,
Dave

 

[Patrick Johnson]

Cornerman:
It's funny... we talked about several versions of "double the distance aiming" over the years at RSB, but I can't find one of the posts!!!

Dave:
If you do, please post a link.

I'm sure we were discussing it on RSB before the turn of the century. Variously called "double-the-distance", "double-the-overlap", etc. It came up often in discussions of aiming systems because it's one of the few "geometrically correct" systems (like ghostball). It's OLD.

It's so well known that it's illustrated on CueTable.com's Aiming Calculator. Here's a snapshot from it. Notice the red X in the center of the CB/OB overlap (the X is part of CueTable.com's image; I added the red curved arrow and text).

Your drawing illustrates doubling the distance from the OB's center to the contact point (and then aiming the CB's center at that doubled distance). The same method also works by doubling the distance from the OB's edge to the contact point (and then aiming the CB's opposite edge at that doubled distance). Doubling from the OB's center is best for shots fuller than half ball; doubling from the OB's edge is best for shots thinner than half ball.

pj
chgo

 

[woody_968]

Could you briefly describe what Don recommends in this regard? It sounds like it might be similar to Gene's PERFECT AIM.

Thanks,
Dave

I have not seen Genes Perfect Aim,,, yet. If I decide to start playing much again I will order it to see what he is doing. From what I have read I dont think it is anything like what Don talks about.

I am left eye dominant and play right handed, so I have messed with eye placement till I made myself dizzy LOL.

In simple terms, when you are down on a shot, and looking at the OB most people will see two cues. If you are left eye dominant you need to aim the cue that you see on the right. And if your right eye dominant you aim the cue on the left. I believe this is with your dominant eye over the cue.

While I have messed with placing the dominant eye over the cue, I dont know that it is right for everyone. I think its more about getting your head in the proper place for YOUR vision to give you the right information. We view everything with both eyes, and feel that this plays a part in pool.

One of the hardest things (IMO) about teaching pool is everyone "sees" things differently. So for me to describe to you what a shot looks like when it is on may be useless. I have talked at length with some of the most respected instructors about sighting and aiming, and have never received what I felt was a complete answer.

I taught for a while under the BCA program, but stopped for two reasons, one of the reasons was I didnt feel like I could answer every question I had about sighting a shot.

When thinks aren't so tight I will order Genes video, and then would be happy to comment on if it has answered the questions that no one else could.

Woody

 

[Majic]

Recently, Don Smith sent me a document describing an aiming system he thinks might be new. I call it the double-the-distance aiming method (d'DAM). He calls it PIM: Pocket Intersection Method. Don asked me to post it and see if people think it is new or not, and to get feedback. I've never seen this presented before, but it is too simple and makes too much sense to be new. Have you guys seen this before in any books or videos? Please give it a try and report back with any feedback or recommendation you might have.

Here's Don's complete document:

"A New Aiming Point Method For Pool" by Don Smith, August 2009​

Here's how it works (per the diagram below):

1. Find the point where a line from the cue ball will intersect the object ball.
2. Find the point where a line from the pocket (or other target) will intersect the object ball.
3. Estimate the distance between these two points.
4. Double this distance to find the aiming point.

PIM doesn't work well when the CB is close to the OB, but it works fine when the balls are farther apart, for all cut angles. It does take a little practice estimating the distances, but you can use your cue tip to help. See the document for more info and examples.

I am sure its on one of Don Feeneys videos.

 

[Dead Crab]

A description of this method appears on pages 4 and 5 of "Answers to a Pool Player's Prayers", (c) 2000, Richard Kranicki.

I would be suprised if it has not appeared in copyrighted material prior to 1900. Falls under the "obvious" category.

 

[Secaucus Fats]

Thanks. Do you know the Copyright year?

Thanks again,
Dave

Thought I'd provide you with the answer to your question...

Private Lessons with Don "The Preacher Feeney"
Lessons 1 thru 8
Copyright 1991--Tight Pockets Video Productions.

The Preacher refers to it as the double the distance system on Lesson I "Sighting and Aiming"

I remember participating in threads about double the distance aiming on both RSB and ASP as far back as '99.

I will fire up the old VCR and watch it again to see if he tells anything about where, when, and how he first learned it.

 

[Pushout]

It's funny... we talked about several versions of "double the distance aiming" over the years at RSB, but I can't find one of the posts!!!

Fred

IIRC, they are saved in Google now? And, they don't go back anywhere near far enough to have access to a lot of stuff.

 

[dr_dave]

PJ,

Thank you for another informative post. I've seen the overlap diagrams before, with the contact point at the center of the overlap region; and I see how this implies the double-the-distance approaches you summarize. I think the difference in Don's document (again the diagram and document are not mine), is that everything is referenced to the CB center. Because of this, the proposed method is not "geometrically correct." It breaks down as the CB gets closer to the OB (see Figure 5 in the document). His document describes a way to practically use a double-the-distance method, where the focus is always through the center of the CB. But again, it is not "geometrically correct" like the parallel-shift, parallel-projection overlap diagrams.

Thanks again for providing the historical context and the CueTable image.

Regards,
Dave

I'm sure we were discussing it on RSB before the turn of the century. Variously called "double-the-distance", "double-the-overlap", etc. It came up often in discussions of aiming systems because it's one of the few "geometrically correct" systems (like ghostball). It's OLD.

It's so well known that it's illustrated on CueTable.com's Aiming Calculator. Here's a snapshot from it. Notice the red X in the center of the CB/OB overlap (the X is part of CueTable.com's image; I added the red curved arrow and text).
View attachment 107886
Your drawing illustrates doubling the distance from the OB's center to the contact point (and then aiming the CB's center at that doubled distance). The same method also works by doubling the distance from the OB's edge to the contact point (and then aiming the CB's opposite edge at that doubled distance). Doubling from the OB's center is best for shots fuller than half ball; doubling from the OB's edge is best for shots thinner than half ball.

pj
chgo

 

[dr_dave]

A description of this method appears on pages 4 and 5 of "Answers to a Pool Player's Prayers", (c) 2000, Richard Kranicki.

I would be suprised if it has not appeared in copyrighted material prior to 1900. Falls under the "obvious" category.

Agreed. I still like Don's document because it shows how double-the-distance can break down (as the balls get closer) if the focus is the center of the CB, and not the parallel shift assumed in the classic overlap diagrams. See Figure 5 in Don's document for more info.

Regards,
Dave

 

[TheBook]

Don Feeney talks about it and demonstrates it in one of his videos.