Thanks Michael

Hi Michael,

>> SimplifyCrv command

Yes I forgot that,i have tried it but i doesn't give
a great result
The FitCurve command is much better

>>The Edit/Separate followed by a Construct/Boolean/Union - Union

I have tried it on a complicated surface and it works great

Thanks PAQ

Hi Paolo,

>> SimplifyCrv command

> Yes I forgot that,i have tried it but i doesn't give
> a great result
> The FitCurve command is much better

FitCrv is used for a much different purpose.

For example, starting with this polyline that has has spans made up of several colinear line segments (note the internal points):



SimplifyCrv produces this result:



FitCrv produces this result:




If you wanted to simplify the line structure to only get the minimal number of points and segments, but still keep the overall shape the same, that is what SimplifyCrv will do. FitCrv fits a new smooth curve through sampled points along that original curve and as you can see the result does not have any line segments in it anymore.

They are used for different situations.

- Michael

Just a little confused here whether we're talking about Rhino or MoI! I'm assuming SimplifyCrv belongs to Rhino?

Michael, do I understand correctly that (currently) if I want to simplify a curve (not a surface) I must remove points manually?

I am working on a way to incorporate embossed lettering onto a flat surface (subject for another thread perhaps).
I have traced the letters from a background image in MoI (using as few points as possible). The problem is that the Offset command (which does a great job) generates curves with far too many points.

I have been thinning them out manually, but seeing this thread made me think there may be a better way??

Steve
Is this something in the style of end result you will need?
Brian

Hi Steve, sorry yes that last part about SimplifyCrv and FitCrv was about Rhino and not MoI (screenshots there were Rhino screenshots).

Right now Offset is oriented towards getting an accurate (and as a side effect heavier) result, when I get a chance to spend some time on that, it should be possible for me to tune that up to reduce the density at least somewhat. But it is a bit of a tricky thing to do it and maintain a good amount of accuracy.

Eventually there will be some commands in MoI for reconstructing a curve, like Rhino's FitCrv or Rebuild commands, but those are not present in MoI quite yet though.

- Michael

Yes Brian

That's about what I'm aiming for. What process did you use? Does your flat sheet have thickness?
I'll probably fillet some of the edges.

The object will eventually be produced in a vacuum moulding process from 3 or 4mm thick ABS (probably) sheet. So part of the problem is to try and predict how small the letters can be before we start losing definition.

Steve

OK, Thanks Michael.

The workaround with Separate and then Boolean Union...I think that doesn't work on curves right?...what objects would that work on?

Hi Steve,

> what objects would that work on?

It works on surfaces that are made up of several smaller planes touching each other edge-to-edge, like this:



After that procedure, those get cleaned up to be only one big plane:



It basically can "heal" many small planar bits into larger single planes.

- Michael

Hi Steve, also one thing that I'm not quite clear on is why are you concerned about the number of points of the Offset result for the particular case that you are working on, are you trying to do additional control point edits to the curve?

You may be interested in this method of doing a tapered style extrude:
http://moi3d.com/forum/index.php?webtag=MOI&msg=941.5

- Michael

Thanks for that clarification Michael

My concern about the number of points is rooted in some vague belief that the file which is to be input to the prototyping machine shouldn't be unnecessarily large. For all I know it may not be an issue!

Also, I'm thinking that if I later perform some boolean operations, a smaller number of points would be better.

The tapered extrude will be very useful.

There are so many jewels hidden in this forum...

Hi Steve, a smaller number is definitely more efficient in file size, but unless you're getting up to like 10,000 of these offsets you probably don't have to worry about it.

Many of the later on operations that are going to be performed on your objects (like meshing or toolpath generation) will generally follow the shape of your object and not automatically become more complicated just because there are more control points in the curves. Instead they will be more complicated in areas of high curvature, not just automatically where there are a higher number of points.

It is particularly not convenient to have a whole bunch of points if you want to edit the shape of the offset curve by tweaking control points around, similar to how you would have edited the very original curve. But for the thing that you're talking about, you probably won't be doing that. Typically for the kind of thing that I think you're doing you would focus your effort on editing the original curve to make it shaped right and not want to edit the resulting offset curve, it is just a thing that is calculated from your edited one.

I'd think that you could probably just not worry about that particular thing for your case...

- Michael

Yes, point taken Michael

After all it is going to be relatively quite a small file.

Thanks again

Steve

Steve
The "sheet" has no thickness.
All I did was to lower the standard 3d letters just a fraction through the sheet and then did some booleans and trim stuff.
Brian
EDIT--No booleans--all cut and trim!

Hi Michael,

>>You may be interested in this method of doing a tapered style extrude:
http://moi3d.com/forum/index.php?webtag=MOI&msg=941.5

In relation to this thread I was just wondering now that we have direct math input in MoI, you mentioned that angle input is in radians, the formula you used in that particular thread to create tapers, is 'Offset dist = Height x Tan( angle )' which is used often in mech eng and nice and easy to input into MoI, but to convert to radians which is: degrees X pi/180 it's a bit annoying is there any way to change the angle input in MoI to degrees ?

Thanks

Hi Danny, re: math expressions angle input in degrees,

Yeah I think that makes sense since this area is for typing stuff in.

It is pretty easy to tweak that and I have set this up now for the next beta. All the trig functions (tan, sin, cos, atan2, atan, asin, acos) will now take or return angle values in degrees with the next beta.

If you do need to use radians for some reason, the radians versions are all still present with an underscore preceding them, like: _cos(PI) that keeps radians input still easy to use if someone feels the urge to type in values in radians... :)

- Michael

Thanks Michael,

Also, it's good that you kept the radians side of things, I do sometimes have that urge to calculate things in radians, usually standing on my head drinking an ice cold coke through my nose :D


Cheers

Thanks Brian

When you say "the standard 3d letters"

did they come from inside MoI or outside?

Steve

Steve
Yes. The standard letter text in the solids.

BUT
Am I pe-empting you with this question about fillets?
Image and file.

Brian

Brian,

I'm embarrased to say that I had never noticed the letters before!

It just proves that you see what you want to see!

Yes that is the sort of look I am after with the filleting...I've continued this as a new topic.

Steve