Circles, snaps and precision

[Daniele]

Hello

I've a small issue here, and I just can't understand why this happens.

 

I need to draw a circle, with a given centre and radius, and I want to introduce as radius the distance between the centre and the intersection of two lines.

 

So, I have the intersection snap actived, and I just click on the centre of my circle and on the intersection of the two lines.

 

Now, the circle should pass through the intersection, right?

Well, with a little bit of zoom I can see that this doesn't happens. The circle it's just a little bit "smaller" than I wanted it to be.

 

Here is an example:

http://dl.dropbox.com/u/12174476/MAM/Esercitazione7/RuoteDentate1.dwg

The purple circle should pass in the intersection between the two purple lines (it should be tangent to the "long" line).

If you zoom, you can see it just doesn't, and it looks like I can't make it coincident.

 

Curious thing is that I can't snap on the intersection between the circle and his "ray" (the purple line which is perpendicular to the tangent), so it looks like Autocad (2011) knows that "that intersection shouldn't exist" but it shows it.

 

I hope I've been able to explain myself

Why does it happens? Do I have to set something?

Thank you

[designerstuart]

it's probably snapped in the right place, just displaying wrong as autocad displays polygons which are not quite circles. sorry i can't see your attachement (fault my end)

[ReMark]

Set WHIPARC=1 and take a second look.

 

BTW, what units are you using and what precision have you specified?

[eldon]

Now, the circle should pass through the intersection, right?

Well, with a little bit of zoom I can see that this doesn't happens.

 

Every time you zoom in, do a Regen

 

Curious thing is that I can't snap on the intersection between the circle and his "ray" (the purple line which is perpendicular to the tangent), so it looks like Autocad (2011) knows that "that intersection shouldn't exist" but it shows it.

 

When you try and snap to the intersection, try making your pick points one at a time to the circle and line at a point where you can see clearly the lines. The Intersection IS there.

[Daniele]

Every time you zoom in, do a Regen

 

This works. So, it's just a display issue. Thank you.

 

Set WHIPARC=1 and take a second look.

 

BTW, what units are you using and what precision have you specified?

 

This one works too (not everytimes: it looks like it does an automatic "regen" every 2/3 steps of zoom.

I've pretty crappy hardware, so I preferred to take it back to 0 and do a manual "regen" when I need.

 

Thank you

[Jack_O'neill]

VIEWRES in your drawing was set to 1000. Pump it up to 10,000 or higher (max of 20,000) and your circle will look much better.

[ReMark]

A setting of 5,000 should be high enough don't you think? 10,000? I don't think I've ever gone that high. I'll have to give it a try and see the results.

[JD Mather]

I've set my viewres to 2000 for years. Regen now and then if needed.

[Jack_O'neill]

A setting of 5,000 should be high enough don't you think? 10,000? I don't think I've ever gone that high. I'll have to give it a try and see the results.

 

All depends on the quality of the graphics card and monitor. The better they are, the lower the setting you can get away with. My current system on anything higher than about 2000 doesn't make much difference. The system I used at my last employer, anything lower than 5000 made all my circles look like stop signs.