# Measuring curved surfaces

#### Rallyboy

##### Newbie
I have a catpart with curved surfaces - on these surfaces are a number of holes - I have created a plane that runs approx. through the centre of the holes and I have then intersected the catpart body with the plane which then creates an intersect line but how do I measure from hole centre to hole centre along this curve (i.e. not shortest distance) - I know you can measure along a surface but I am having trouble pointing points on the intersection line at the hole centres and trimming the line back to these for some reason - Any advise anybody ??

#### Rallyboy

##### Newbie
New to forum - measuring curved surfaces

I have a catpart with curved surfaces - on these surfaces are a number of holes - I have created a plane that runs approx. through the centre of the holes and I have then intersected the catpart body with the plane which then creates an intersect line but how do I measure from hole centre to hole centre along this curve (i.e. not shortest distance) - I know you can measure along a surface but I am having trouble pointing points on the intersection line at the hole centres and trimming the line back to these for some reason - Any advise anybody ??

#### MrCATIA

##### Super Moderator
Rallyboy,

I don't see any option to measure along a surface, so you'll have to create a curve on the surface between the two centerpoints and then measure the length of the curve.

For each measure:
1. create points at the center of the two circles
2. add a PT-PT line between the two centerpoints, with the surface as the support
3. measure the length of the curved line

#### Rallyboy

##### Newbie
Continuous Line - Or not ??

Ah I was intersecting the part with a plane I had created after I had extracted the surfaces and was then splitting the intersection line with points (that were on the hole centres), but then used your idea by creating a line pt-pt and using the surface as the support, but as I have extracted several surfaces there are changes in section and even though I have joined the extracted surfaces together (surfaces now in a Geometrical Set I created) I still have issues when I create a line using two points due to different areas of this joined surface being created from different surfaces and the line looks continuous but when you click on it it actually only shows that part of the line until it meets the next change in section - if you can understand that ?? - Bizarre what am i doing wrong ??

I have another annoying query, if some holes are on a change in section so when you click them the were effectively two half a holes (I know you can't get half a hole but just to explain), so when in GSD and you create point using circle / sphere centre it fails when you select the hole edge as it sees it as two holes - Any advise ??

Just a note on measuring along a surface - I was measuring the length along the curve using the measure item icon (4th from left - the calipers) and I appreciate there isn't a measure along surface, as such, button I just wanted to differential between that and measuring the shortest distance as this will not be along the curved surface

Thanks

#### MrCATIA

##### Super Moderator
Could you attach a picture of what you're working with - it would help tremendously to understand

I think you're saying the surface is stepped. Do you want the measurement to include the step distance?

(I'm wondering if maybe using a flat pattern might be a better way to get the measurement - how accurate must the measurement be?)

And yes, the shortest distance with the calipers measure will be a straight line between two points,

#### Rallyboy

##### Newbie
V5 - Curve Smooth in GSD

What are the benefits of Curve Smooth in GSD and when would you use it ??