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SAC: Intersection Point. Point not found?

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Message 1 of 19
doni49
745 Views, 18 Replies

SAC: Intersection Point. Point not found?

I have a custom SA that I created in SAC 2012. 

 

It has an AuxSurfaceLink (AL1) and an AuxLink (AL10).  Then I have an "Intersection Point" (AP13) that is set to the intersection of these two links.  When my corridor tries to rebuild, I get an error message that AP13 could not be created at station 2+05.

 

I opened the Section Viewer and see no reason for the point not to be created.  If you look at the following image, it is a screen shot of the section at 2+05.  The white lines are what I drew in there manually.  AP13 should not be a problem.SAC SurfaceLinkIntersection.png



Don Ireland
Engineering Design Technician




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18 REPLIES 18
Message 2 of 19
fcernst
in reply to: doni49

Auxillary Points and Links do not get created in the Civil 3D modeling environment.



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
Message 3 of 19
MKearney028
in reply to: doni49

We need more details, but if AL10 cannot hit AL1 within the surface limits, it will give you that error. Surface links have a hard time with extensions.
So how is AL10 being created?
There may be an error before AP13 that is not allowing the subassembly to continue to be created.
Message 4 of 19
doni49
in reply to: fcernst


@fcernst wrote:

Auxillary Points and Links do not get created in the Civil 3D modeling environment.


I know that.  But the SA uses the AuxPoints and AuxLinks to create points and links that C3D DOES create.  The first error message in Panorama says that AP13 was not created.  Then there are several error messages about other points and links not being created but those depend upon AP13.  Once AP13 is works, the others should go away.  And this is ONLY happening at 2+05.  The corridor is 290 ft long and the frequency is set to 5 ft.

 

EDIT:  Here's a screen shot of Panorama.

SAC SurfaceLinkIntersectionPanorama.png



Don Ireland
Engineering Design Technician




If a reply solves your issue, please remember to click on "Accept as Solution". This will help other users looking to solve a similar issue. Thank you.


Please do not send a PM asking for assistance. That's what the forums are for. This allows everyone to benefit from the question asked and the answers given.

Message 5 of 19
doni49
in reply to: MKearney028


@MKearney028 wrote:
We need more details, but if AL10 cannot hit AL1 within the surface limits, it will give you that error. Surface links have a hard time with extensions.
So how is AL10 being created?
There may be an error before AP13 that is not allowing the subassembly to continue to be created.

I understood that which is why I examined where AP13 should be created.  In the cross section editor, I used the same criteria that I defined the SA to use and manually drew the lines that the assembly should be creating.



Don Ireland
Engineering Design Technician




If a reply solves your issue, please remember to click on "Accept as Solution". This will help other users looking to solve a similar issue. Thank you.


Please do not send a PM asking for assistance. That's what the forums are for. This allows everyone to benefit from the question asked and the answers given.

Message 6 of 19
fcernst
in reply to: doni49

If that white line you drew is AL10, I don't see any surface intersection?

 

What surface is it suppose to intersect with? Is one of the red lines your target surface?



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
Message 7 of 19
doni49
in reply to: fcernst

Here's a screenshot of the preview window from SAC.  This should help you understand what I'll try to explain.

 

AL1 is an AuxSurfaceLink with a DEPTH of 2ft.  So in the Section Editor, I drew a polyline on top of the surface and moved it down 2 ft.

 

AP5 is a point created by going from AP4 (the slope daylight point) and turning 90 degrees (referencing the bottom of the ditch (P17).  Then P16 is the bottom of the material layer below point P17.  This is seen in the previous screen shot as the location where my white line meets the yellow line (C3D created the yellow line correctly).

 

AL10 is created between AP5 and P16.

 

AP13 is SUPPOSED to be the intersection of AL10 and AL1.

 

SAC SurfaceLinkIntersectionPreview.png



Don Ireland
Engineering Design Technician




If a reply solves your issue, please remember to click on "Accept as Solution". This will help other users looking to solve a similar issue. Thank you.


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Message 8 of 19
doni49
in reply to: doni49

Attached is a dwg file with my surface, alignment, profile and corridor.



Don Ireland
Engineering Design Technician




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Message 9 of 19
fcernst
in reply to: doni49

Make a version with real points, and let's see where they line up. AP5 may be ending up below the surface offset.



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
Message 10 of 19
doni49
in reply to: fcernst

Nice troubleshooting suggestion.  I'll have to remember that one.

 

I created a point (P23) with a delta x and delta y of 0 relative to AP5 (basically making it on top of AP5).  Then to make the points stand out, I created two additional points (P22 and P21).  I added links between P22 & P16, P16 & P23, and P23 & P22.  I also made a SurfaceLink (not an aux) on top of AL1.

 

Here's a screenshot of the preview window with those changes.

 

SAC SurfaceLinkIntersectionPreview2.png

 

After saving and importing the updated SA, here's what the cross section editor shows.  You're right, AP5 IS below the AuxSurfaceLink and even with "Extend Link" turned on, it will not improve.

 

Now I need to figure out WHY that is.  When I manually drew the line work using the criteria specified in the SA, it works fine.

 

Thanks for all the help!

 

SAC SurfaceLinkIntersection2.png



Don Ireland
Engineering Design Technician




If a reply solves your issue, please remember to click on "Accept as Solution". This will help other users looking to solve a similar issue. Thank you.


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Message 11 of 19
doni49
in reply to: doni49


@doni49 wrote:

 

Now I need to figure out WHY that is.    

 



I just realized the problem.  The SurfaceLink "Depth" parameter doesn't copy the surface PARALLEL, it copies it STRAIGHT DOWN. 

 

At this one location, that just doesn't go deep enough for the intersection to occur.



Don Ireland
Engineering Design Technician




If a reply solves your issue, please remember to click on "Accept as Solution". This will help other users looking to solve a similar issue. Thank you.


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Message 12 of 19
doni49
in reply to: doni49

Is there a way to use a a WHILE loop in SAC?  Since my point just barely misses the surface link, what I'd like to do is something like:

 

RockDepth = RockBlanketDepth + 0.05)

while(not(AP13.isvalid)){

  RockDepth = RockDepth - 0.05

  attempt to create AP13 using RockDepth

}

 

The theory is that it would gradually reduce the depth and hopefully eventually create the point.



Don Ireland
Engineering Design Technician




If a reply solves your issue, please remember to click on "Accept as Solution". This will help other users looking to solve a similar issue. Thank you.


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Message 13 of 19
fcernst
in reply to: doni49

No, but you can just figure out where AP5 is relative to the surface offset (depth), then do something.



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
Message 14 of 19
doni49
in reply to: fcernst

I've spent the afternoon trying to figure out how I was going to accomplish that.  I even got out the old Trig formulas.



Don Ireland
Engineering Design Technician




If a reply solves your issue, please remember to click on "Accept as Solution". This will help other users looking to solve a similar issue. Thank you.


Please do not send a PM asking for assistance. That's what the forums are for. This allows everyone to benefit from the question asked and the answers given.

Message 15 of 19
doni49
in reply to: doni49

Thanks for all the assistance! 

 

As I already said, once I used your suggestion of adding points to see if/where they fell, I found that it really was having trouble locating the intersection point.  I'll go back and mark that reply as a solution as it was PART of the solution and without it, I wouldn't have found the problem.  It'll be important for people having similar issues to see that.

 

Anyway, I figured out how to use AP5's location to identify the desired depth.  First, here's a screenshot of the graphic I made to help me figure it out.

 

 

 

SAC SurfaceLinkIntersectionSolved.png

 

First I know that the angle between link L11 and line AP4-AP5 will ALWAYS be 90.  So I used that to figure out the angle between line AP4-AP5 and the vertical (in this case that angle is 43 which I'll call THETA).  I changed AP13 so that it is relative to AP4 at an angle from the vertical of THETA divided by 2 and a distance of 10.  Then I made an AUXLINK (AL15) from AP4 to AP13.  The intersection of AL15 and AL10 gives me the exact point where I want the bottom of my material to intersect with AL10 -- that's AP29.

 

Lastly, I changed the surface link definition's DEPTH to AP29.distancetosurface(Surface).  Since the depth is specifically controled by the distance from the point up to the surface, I'm guaranteed that it will go through the point (as long as the surface is actually above it).

 

The whole corridor is working without even a single error.

 

EDIT:  To figure out the THETA angle, I used math.acos(AP4.slopeto("AP5")).



Don Ireland
Engineering Design Technician




If a reply solves your issue, please remember to click on "Accept as Solution". This will help other users looking to solve a similar issue. Thank you.


Please do not send a PM asking for assistance. That's what the forums are for. This allows everyone to benefit from the question asked and the answers given.

Message 16 of 19
fcernst
in reply to: doni49

Don I
 
"Credit where credit is due! Give kudos or accept as solution whenever you can. "
                                        -- troma

 


Why do you have this in your signature? No Kudos given...and you gave yourself the Solution!  

 

😉



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
Message 17 of 19
doni49
in reply to: fcernst


@fcernst wrote:

Don I
 
"Credit where credit is due! Give kudos or accept as solution whenever you can. "
                                        -- troma

 


Why do you have this in your signature?


 I just liked how it sounded when I read it in troma's signature.  So I decided to say the same thing in mine.  And I noted that it was a quote from him because I thought it was especially fitting as in "giving credit where credit is due".


@fcernst wrote:
No Kudos given...and you gave yourself the Solution!  

I marked my latest reply as solution because as far as I know, that system is more about helping users find solutions to their own problems.  If someone is ever searching for a solution to a similar problem, they're able to "look past" all/most of the interim messages and see what the final solution was.  The only reason for posting the message in the first place was in hopes that it might help someone else in the future.  I for one don't even pay attention to how many "Solutions" there are listed under my name.  I post replies to people's queries in hopes that I might be able to "pay it forward" as I recognize that I've been helped here immensely.  If someone marks one of my replies as a "Solution" then maybe it'll help another person down the road too to try and find answers known to have worked.  Beyond that, I don't really care about the "Solution" system.



Don Ireland
Engineering Design Technician




If a reply solves your issue, please remember to click on "Accept as Solution". This will help other users looking to solve a similar issue. Thank you.


Please do not send a PM asking for assistance. That's what the forums are for. This allows everyone to benefit from the question asked and the answers given.

Message 18 of 19
fcernst
in reply to: doni49

..that system is more about helping users find solutions to their own problems.  If someone is ever searching for a solution to a similar problem,..

 


The sloution you chose to reference in this thread is too specific and obscure to your problem at Sta 2+05 to be of help to the general audience with a desire to learn SAC principles. It's mostly discusses general trigonometry.

 

I demonstrated how to analyze an Auxillary Intersection problem in SAC for you, and then speculated that your intersection link was not being created because the endpoint of your intersecting link was below your auxillary surface link that is using a depth parameter. That solved your question why AP13 was not being created.

 

I thought you said you were going to mark that as the Solution.

 

"Credit where credit is due! Give kudos or accept as solution whenever you can. " 

-troma
                                     

Again, Still no Kudos?

 

 



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
Message 19 of 19
doni49
in reply to: fcernst


@fcernst wrote:

..that system is more about helping users find solutions to their own problems.  If someone is ever searching for a solution to a similar problem,..

 


The sloution you chose to reference in this thread is too specific and obscure to your problem at Sta 2+05 to be of help to the general audience with a desire to learn SAC principles. It's mostly discusses general trigonometry.

 

I demonstrated how to analyze an Auxillary Intersection problem in SAC for you, and then speculated that your intersection link was not being created because the endpoint of your intersecting link was below your auxillary surface link that is using a depth parameter. That solved your question why AP13 was not being created.

 

I thought you said you were going to mark that as the Solution.

 

"Credit where credit is due! Give kudos or accept as solution whenever you can. " 

-troma
                                     

Again, Still no Kudos?

 

 


Actually, I DID mark your suggestion as solution and when you someone reads the OP message, there is a link "Click for Solution" and clicking that link will take the user to your message.  I realize that my post was rather specific to my situation.  But it was my hope that it might stimulate some thought in that direction for whomever eventually reads the thread.

 

As to the Kudos, I do tend to forget about them.



Don Ireland
Engineering Design Technician




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