Is there an easy way to wind the maximum perpendicular point between two lines?
I'm trying to find the maximum perpendicular distance between two lines and the measure tools don't seem to have a function for this. I'm currently copying parallel to find the point but it's a bit slow and imprecise, is there a better way of doing this?
The attached image should show what I'm trying to do.
Offset the yellow line a significant distance beyond the red, and construct a minimum distance line between the 2
in your example its an arc and a line there is a mathematical solution with equation ( google chord height) to find out the height of a cord so you could use the calc to check your answer but I would use place circle by edge and use tangent and perp snaps and Mstm will find the solution as the diam of the circle.. all the equations are here
www.mathopenref.com/sagitta.html
Lorys
Started msnt work 1990 - Retired Nov 2022 ( oh boy am I old )
But was long time user V8iss10 (8.11.09.919) dabbler CE update 16 (10.16.00.80)
MicroStation user since 1990 Melbourne Australia.click link to PM me
Lorys said: I would use place circle by edge and use tangent and perp snaps and Mstm will find the solution as the diam of the circle
That won't work either for the simple reason, how do you know that your chosen start point of the circle is precisely at one of the 2 possible furthest points? You're eye-balling it and that is not an accurate solution to the problem.
The idea of circle theory may not even be applicable; the op stated in the title and original post that its the maximum distance between 2 lines (not Circle/Arc). That what appears to be Circle/Arc in the image, may/may not be relevant. Regardless, the option proposed by both myself and MaryB is the only one which I can think of right now which will give the OP a way to accurately attain the maximum distance between 2 lines/arcs etc...
That's something I had never come across! I looked up sagitta and wrote a VBA macro to create one...
Regards, Jon Summers LA Solutions
Barry Lothian said:how do you know that your chosen start point of the circle is precisely at one of the 2 possible furthest points?
I'm not so sure your right as if its an arc then tangent snap from arc and perpendicular to the line should result in an mstn solving or solution.. maybe my test file was too simple with an arc as part of semicircle and a chord 2/3 up from diameter but I like Jon's vba pretty clever...
Lorys said:maybe my test file was too simple with an arc as part of semicircle and a chord 2/3 up from diameter
I'm absolutely correct without a doubt, I've tested your suggestion and found it doesn't work. Your description of your test case gave you false hope; by creating an arrangement of a perfect chord on a circle/arc, you automatically gained one of the furthest points via the mid point of the line. If you try a test with a different situation using a partial arc or line, you will find it will fail. Why? Simply because, the line's midpoint is no longer one of the furthest opposing points AND when using the command PLACE CIRCLE DIAMETER, MicroStation prevents perpendicular snap from being used (unlike with PLACE LINE as per Ron's suggestion) thus killing your idea immediately.
Only because you were able to key-point snap to the line's mid-point, were you then able to create the circle via tangent snapping to the opposing furthest point, but unfortunately as a reusable solution in all circumstances, the result was a false positive.
Ron's suggestion is the best answer to the OP's query.
Barry Lothian said: of your test case gave you false hope; by creating an arrangement of a perfect chord on a circle/arc
Ok my bad .. consider the point conceded but thanks for figuring it out where I was going wrong .. but to be fair I did go off the OP image as his example but I didnt think it thru enough about the top of the arc has to be the furthest point in a perfect case.. and I agree that Ron Jones is the best and least effort approach for all situations... however the assumption was the OP wanted the Sagitta length ... ( which I often need in my work too) inspired Jon Summers to create and share his new VBA macro for which I'm grateful and others with definitely benefit although serendipitously arrived at... and the create centre line is also awsome..