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Banging my head on the wall with this one...

Google searches so far null...

I have a ton of over lapping circles in a mapping program...they represent radar ranges for installations such as fixed operating bases, strategic facilities, anti-aircraft assets...

Most if not all overlap one or many of their bretheren...some may stand alone...Imagine an outlying installation with limited range...

I am trying to draw the UNION of the aggregated collection of circle objects...technically ellipses bound by rectangles...

I am trying to draw the outside boundary of the air defense system...I want to eliminate all drawing of the portion of the child ellipses that fall within that outer boundry...

If an outlying station is standing alone so to speak it should be drawn as a simple circle...

Should I link a picture?

What the heck here it is...image is a bit big so I linked it

image 1024x1024

What I want to draw is union outline of the British and then of the Germans...

So far I can't figure out how to this in C# GDI...

I Do not want to fill the path using the Winding Mode Flag...I want to Draw the OUTLINE..

Any help greatly appreciated...

Oneway

Oneway
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  • Why not just draw it in solid colour? – Anon. Feb 26 '10 at 03:23
  • Just to note in this particular example their three orphan rings that form their own union for the British at the bottom of the map...that's in the details...all I need is a method that takes two circles that overlap and in essence draws the figure-8 outline...I can figure the rest out from their... Again many thanks to any that help on this one... – Oneway Feb 26 '10 at 03:24
  • If it was drawn solid then the map would be occluded by the fill or brush...the idea is to reduce the visual clutter of the numerous overlapping rings and simply define the extents of the aggregated radar area...the maps my program produce are used in planning the re-enactment in real-time of the air battles of World War II...in this particular case we are re-enacting online with over 300 players in a first person WW2 flight sim...we use these maps for planning, analysis and refinement...we cannot have the details of the map occluded with a fill...we need the outline... – Oneway Feb 26 '10 at 03:32
  • Is there any reason you have to stay with regular drawing? This would be fairly trivial in DirectX and I can imagine a solution with WPF, but anything I envision with GDI would be too slow... – Travis Gockel Feb 26 '10 at 03:37
  • I am a novice programmer self taught...heck I am actually a carpenter that codes as a hobby (love code)...many times I have Googled and found pointers to DX...but I have never gone down that road...YET... For now I need a GDI solution...but it is quite apparent...that I must roll this program out of GDI to DX...NOT YET...not now...If I can get a GDI solution to work for now that would be great...but I am hearing you...and I can sense sooner rather than later I must migrate (UGH)... – Oneway Feb 26 '10 at 03:42
  • By the way...shoot me your top pick(s) of sites/links for a guy that is ready to move from GDI drawing to DX...I need a primmer that x-refs GDI methodology with DX...that makes sense and argues for the transition.. – Oneway Feb 26 '10 at 03:46
  • So far...waiting for kludged gdi approach to this...and anticipating DX insight – Oneway Feb 26 '10 at 05:17

1 Answers1

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Create a new image, render the circles in solid colour to that area, then overlay that image on your map at, say, 50% opacity.

Alternatively, run an edge detect on that solid-colour image to find the overall outline.

Anon.
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  • I apologize for my naivete.. Explain "edge detect"...and you don't have to in neophyte terms...what is the gist of "edge detection"? ...sounds ram intensive...top heavy – Oneway Feb 26 '10 at 03:55