Boundary Precision

[cadsterdyne]

Hi Forum.

 

Great tool this boundary command, but is there a way to increase precision as in attached drawing i observed that when i zoom out till all the objects are visible and pick a point somewhere for the boundary command there are a few places where the boundary formed is merging the two objects in one boundary as there is a minute gap there.

 

is there way to increase the boundary command precision?

 

Thank you in advance.

BOUNDARYPRECISSION.dwg

[marko_ribar]

Hi, I've developed and better version than this, but I don't want to share it as it uses some portions of copyrighted material... But at least you can try with this posted here (you must have A2012+) and be sure to check and reset undocumented sysvar 'QAFLAGS to 0 after routine executes...

 

http://forums.autodesk.com/t5/visual-lisp-autolisp-and-general/alternative-of-boundary-in-the-mode-of-pick-point/m-p/6391996/highlight/true#M342208

 

HTH, M.R.

[marko_ribar]

I only now looked in your DWG... I think that link I provided can't help you... You must use BPOLY command and after boundaries are created you have to manually fix those red ones, but as I see you already had POLYLINE/REGION boundaries not LINES or simple entities that are forming boundaries, I don't see the purpose of doing this after all - you have the resulting DWG with all correct boundaries...

[marko_ribar]

One more thing to add... And if you have simple geometry LINES, ARCS, and so on... forming boundaries, I suggest that you use REGION command and CAD will automatically create REGION boundaries of selected objects... Then if simple geometry entities were LINES and ARCS, you can EXPLODE REGIONS and use PEDIT "Multiple" option after you can use "_Join" option with small and appropriate fuzz factor to form LWPOLYLINE entities - boundary entities more desired than REGIONS IMO...

[eldon]

i have a feeling (and someone can state otherwise) that the boundary command depends on the screen resolution. It cannot resolve less than a pixel or a bit less. That is why your boundaries are not matching your shapes.

 

If you zoom in, the boundary command works perfectly.

 

I do not think that there is any system variable which will enhance your actual screen resolution.

[cadsterdyne]

Hi, I've developed and better version than this, but I don't want to share it as it uses some portions of copyrighted material... But at least you can try with this posted here (you must have A2012+) and be sure to check and reset undocumented sysvar 'QAFLAGS to 0 after routine executes...

 

http://forums.autodesk.com/t5/visual-lisp-autolisp-and-general/alternative-of-boundary-in-the-mode-of-pick-point/m-p/6391996/highlight/true#M342208

 

HTH, M.R.

 

Thank you anyway marko_ribar for the link above sure helps for learning something else !!

[cadsterdyne]

I only now looked in your DWG... I think that link I provided can't help you... You must use BPOLY command and after boundaries are created you have to manually fix those red ones, but as I see you already had POLYLINE/REGION boundaries not LINES or simple entities that are forming boundaries, I don't see the purpose of doing this after all - you have the resulting DWG with all correct boundaries...

 

marko_ribar the reason i am doing this is because of all those rectangles there, some are overlapping which are hidden one above the other... i used the overkill command to get some cleared but still there are some duplicates leftover. and some how i thought of using the boundary command and filtering out the new boundaries so that way i can reduce the overlapping objects.

[cadsterdyne]

I haven't used the region command yet, sure i will give a try as you described marko_ribar.

Thank you.

[cadsterdyne]

i have a feeling (and someone can state otherwise) that the boundary command depends on the screen resolution. It cannot resolve less than a pixel or a bit less. That is why your boundaries are not matching your shapes.

 

If you zoom in, the boundary command works perfectly.

 

I do not think that there is any system variable which will enhance your actual screen resolution.

 

 

You are right eldon.

i have tried zooming in and creating boundaries and it works flawlessly. the problem is when i get all objects in view and try creating the boundaries, i tried setting limits for the drawing very close to the extent of all the objects , No luck,

searched the internet a bit found HPGAPTOL variable could be adjusted but it is already set to zero. no help there.

[lrm]

Since you are using 2D Wireframe as the Visual style I think the problem lies with the 2D display list that is used and not the screen resolution.

 

Try the following:

1. Open the drawing and do a zoom extents.

2. Zoom in on the drawing with z [enter] 10x [enter]

3. Give the regen command to rebuild the display list at a higher precision.

4. Zoom out with the scroll wheel and try the boundary selection.

 

~Lee

[marko_ribar]

Since you are using 2D Wireframe as the Visual style I think the problem lies with the 2D display list that is used and not the screen resolution.

 

Try the following:

1. Open the drawing and do a zoom extents.

2. Zoom in on the drawing with z [enter] 10x [enter]

3. Give the regen command to rebuild the display list at a higher precision.

4. Zoom out with the scroll wheel and try the boundary selection.

 

~Lee

 

@Lee

No that's not it... I've just tried ZOOM "Center" pick point in center of right portion - type factor : 200 => REGEN => ZOOM "V" to zoom out maximum - should display all right portion => BPOLY pick internal point - incorrect number of POLYLINES are created and you can see that narrow passages between them are jumped over and bigger single boundary is created when zoomed to corresponding "red" examples entities from left portion and it should create 2 separate smaller boundaries...

[lrm]

@Lee

No that's not it... I've just tried ZOOM "Center" pick point in center of right portion - type factor : 200 => REGEN => ZOOM "V" to zoom out maximum - should display all right portion => BPOLY pick internal point - incorrect number of POLYLINES are created and you can see that narrow passages between them are jumped over and bigger single boundary is created when zoomed to corresponding "red" examples entities from left portion and it should create 2 separate smaller boundaries...

 

Regen does affect the precision of the boundary pick. After your Zoom View the geometry is fairly small and difficult to get a screen pick inside one of the problem shapes (Note, Zoom V does not recalculate the display list whereas zoom e does, so you are OK using Zoom V). When I do pick inside the shape after the zoom v the boundary is successfully created. I did the same process using zoom e and did create a boundary that did merge shapes proving that regen does affect precision.

 

~Lee

[eldon]

.....When I do pick inside the shape......

 

I think that the OP was trying to save having to pick 420 times by having one rectangle surrounding all the shapes, and then picking once, inside the large rectangle.

[cadsterdyne]

I think that the OP was trying to save having to pick 420 times by having one rectangle surrounding all the shapes, and then picking once, inside the large rectangle.

 

Very Right eldon.

if the bpoly command is so much to do with the resolution..then would higher resolutions on a 4k monitor with a good graphics card make it work

would not go buying a 4k monitor for this though.

[marko_ribar]

Ha, ha, it has nothing to do with monitors - monitors are peripheral devices... It has something to do with how CAD works REGEN, ZOOM, etc. Graphic card is also not an issue...

[lrm]

On further inspection it looks like REGEN does not affect the results of the size of the gap detection by the bpoly command. It is a function of how zoomed in the image is. I created temporary boundaries to find a threshold for gap detection. The image below shows the approximate largest area I could display and get gap detection.

[eldon]

Pursuing my hypothesis that the minimum gap detection is linked to the display pixels, I carried out a little quantitative test.

 

First of all I tried to find the minimum gap in the posted drawing. I found one gap of 20.9 drawing units. I then found out my screen size in pixels (x,y) from the command SCREENSIZE. I then multiplied these by 40 (to give the sense that the gap was half a pixel), and drew a rectangle of these dimensions.

 

I zoomed to the window given by the rectangle. Bpoly found all the gaps in that area. It worked for me.

[marko_ribar]

Conclusion : Minimal gap that can be detected by BPOLY is more than 1 pixel of current display zoomed area... But like I said in post #4, sometimes REGION command is the right way to accomplish such tasks...

[eldon]

Conclusion : Minimal gap that can be detected by BPOLY is more than 1 pixel of current display zoomed area...

 

My findings were that the minimum gap detected was half a pixel. But someone may the know the definitive answer.

[Debalance]

Hi Forum.

 

Great tool this boundary command, but is there a way to increase precision as in attached drawing i observed that when i zoom out till all the objects are visible and pick a point somewhere for the boundary command there are a few places where the boundary formed is merging the two objects in one boundary as there is a minute gap there.

 

is there way to increase the boundary command precision?

 

Thank you in advance.

 

There is a more powerful free tool that allows you to easily solve the problem. This is SuperBoundary: