Average Normals; Porcelain

[sb4]

In the help for A:M 10.5 there is reference to surface properties Average Normals and Normal Weight. I can't seem to find them the the properties for an object I have in a Model window. The reference says:

 

Average Normals Visible: Sometimes, Advanced, Default: OFF

Hash patch models offer a surface fidelity and low-density unmatched by other modeling techniques which gives them the natural appearance of organic and earth made objects. Manmade technology produces its own smooth surface, and many models constructed using competing methods (such as polygons) have the ultra-smooth appearance of glazed ceramics. This property allows you to achieve this porcelain look, on your models. This option averages the surface normals, so much of the model's details will be lost, and it may shade oddly if the object is distorted during an animation.

 

I read some other posts that say you need to toggle "Render As Lines" on the group under "Groups" for your model, and then the properties will show up. Hasn't worked for me.

 

Also, some suggest you need to first apply the Porcelain material to your model. I did that (dragged onto model), but still don't see the "Average Normals" property, and do not see these properties anywhere.

 

Is there an "Advanced" mode I need to engage to see these properties?

 

Any more ideas on how to get to these "Normal" properties?

 

 

-SB

[robcat2075]

That's a new one to me!

 

"Show Advanced Properties" is an option on your Global tab

 

With that checked, make a Group in your model, then in its properties toggle Render as Lines ON and OFF and two new mystery properties appear at the bottom of "Surface": Average Normals and Normal Weight.

 

You may need to refresh the display to make any change to the settings show.

 

 

It seems to be somewhat like the "porcelain" material they added later. The appearance is not dramatically different but can be noticeable in some cases.

[robcat2075]

Update: I just found that these two properties still exist in v17.

 

Who knew?

 

Hmmm... this may be big! It solves a long standing annoyance I've had with lathed objects.

 

Below5 is a semi-top view of a lathed cone shape. If you look at the top version you'll see there is slight pattern to the shading that radiates from the center.

 

With "Average Normals" ON and Normal Weight set to 0% it exhibits the same pattern.

 

With "Average Normals" ON and Normal Weight set to 50% the pattern is gone.

 

With "Average Normals" ON and Normal Weight set to 100% the pattern is back with opposite shading.

 

[sb4]

That's a new one to me!

 

"Show Advanced Properties" is an option on your Global tab

 

With that checked, make a Group in your model, then in its properties toggle Render as Lines ON and OFF and two new mystery properties appear at the bottom of "Surface": Average Normals and Normal Weight.

 

You may need to refresh the display to make any change to the settings show.

 

 

It seems to be somewhat like the "porcelain" material they added later. The appearance is not dramatically different but can be noticeable in some cases.

 

Thanks - turning on Advanced and toggling RAL on/off (crazy) exposes the properties.

 

That's an interesting example you posted. It almost looks like the splines underneath the surface are ever so slightly having an effect until you use 50%.

 

Every little property is a gem!

 

-SB

[robcat2075]

I'm sure having to toggle Render as Lines is a bug.

[Fuchur]

Very nice find...

Something I was always wondering about was these additional buttons "Biased Normals" and "Perpendicular Bias" in the Add-Toolbar (at least you can add them there if they are not available using Tools > Customize.

 

They do something to the objects you are setting them too, but I am not sure what it is and what they can do for the artist.... maybe this can help too with the smoothness of an object.

 

See you

*Fuchur*

[Rodney]

Something I was always wondering about was these additional buttons "Biased Normals" and "Perpendicular Bias" in the Add-Toolbar (at least you can add them there if they are not available using Tools > Customize.

 

They do something to the objects you are setting them too, but I am not sure what it is and what they can do for the artist.... maybe this can help too with the smoothness of an object

 

This relates to the rotational orientation of the patch.

A way to test this out is to apply an image to a patch with that image indicating direction and then start flipping the normal back and forth multiple times.

While flipping normals note there are more than two states, which is what would be the case if it was a binary choice between forward and backward (it behaves closer to what is observed when using Rotate Image but unlike rotating the patch image it does not invert the normal from the top surface of the patch to the reverse).

 

It would be possible to color code the normal (visual spike) in order to be able to better visualize the orientation and rotation but I'm guessing there is even more going on here than my pea sized brain can absorb.

 

This has a lot to do with the order in which a spline is laid down (i.e. a spline's and therefore a patches default orientation).

To test this you can draw a single spline from left to right and then extrude that spline down into a patch, then Right Click and Apply Image.

Go back and draw a new spline but this time draw from right to left... extrude to a plane... and again Right Click and Apply Image.

You should see that in each case the images are inverted from each other.

 

So... what does this mean?

Basically, it means that the direction that you draw splines matters.

It matters because the direction of the spline(s) will determine the orientation and rotation of the normals.

The normals in turn control the surface properties... patch images, textures, etc. ...and the orientation thereof.

 

I haven't tested but I believe some of the plugins that average normals look through a series of normals and eliminate the oddly oriented ones through the process of averaging them out. A program/plugin can also determine which normals are not correctly oriented by playing the old game of 'which one of these things is not like the other'.

 

Now a question I might ask would be... Is there a way have the orientation of a spline/normal always point to one location?

The simple answer is 'yes, but no' mainly because of the nature of an object in three dimensions and we tend to think of (visualize) normals in terms of two dimensions. I believe this is where things like weighted CPs, fall off and such comes in.

 

How to better control this stuff?

Perhaps we need to learn better how spline orientation works but this is a complicated thing because while a single spline can only have one (linear/path) direction the patches derived from it can have any number of different orientations (at least six non linear directions... that is to say non continuous orientations... if I understand this correctly).

[robcat2075]

Very nice find...

Something I was always wondering about was these additional buttons "Biased Normals" and "Perpendicular Bias" in the Add-Toolbar (at least you can add them there if they are not available using Tools > Customize.

 

We had a brief discussion about them a while back...

 

http://www.hash.com/forums/index.php?showt...3&hl=biased

[sb4]

Something I was always wondering about was these additional buttons "Biased Normals" and "Perpendicular Bias" in the Add-Toolbar (at least you can add them there if they are not available using Tools > Customize.

 

They do something to the objects you are setting them too, but I am not sure what it is and what they can do for the artist.... maybe this can help too with the smoothness of an object

 

This relates to the rotational orientation of the patch.

A way to test this out is to apply an image to a patch with that image indicating direction and then start flipping the normal back and forth multiple times.

While flipping normals note there are more than two states, which is what would be the case if it was a binary choice between forward and backward (it behaves closer to what is observed when using Rotate Image but unlike rotating the patch image it does not invert the normal from the top surface of the patch to the reverse).

 

...

 

How to better control this stuff?

Perhaps we need to learn better how spline orientation works but this is a complicated thing because while a single spline can only have one (linear/path) direction the patches derived from it can have any number of different orientations (at least six non linear directions... that is to say non continuous orientations... if I understand this correctly).

 

Would you expand on how a patch has multiple "normals", and how a normal is defined in A:M?

 

I think of a normal vector as being defined at a single point on a surface, and would have a direction. I can only think of "flipping" as reversing the direction.

 

On a flat surface such as a polygon, all the normals would be parallel and thus could be represented directionally by a single vector. However on a general spline patch that happens to not be flat, there would be "infinite" normals, one for each point. So I'm not clear on what is meant by the "normal for a patch". Is there a specific definition for a patch normal?

 

-SB

[Rodney]

Would you expand on how a patch has multiple "normals", and how a normal is defined in A:M?

 

A surface will only have one Normal but that normal can be oriented differently based on several things; how the surface was formed for instance and what the global parameters are.

 

If you are that interested...

To understand more fully how Normals work in A:M you may want to review Martin Hash's algorithm for hash patches and splines where the word 'normal' is used at least 20 times:

 

http://www.ibiblio.org/e-notes/Hash/Hash.htm

 

While a surface really has only one Normal (used to define the orientation of that surface), each Control Point similarly has the equivalent of a Normal in order to define the direction of the spline. These 'normals' are perhaps better defined as Bias Handles because they handle the given biased/direction of the spline.

 

There is in A:M an extra set of tools that can be added to our toolbar that allows us to toggle on/off Biased Normals.

 

Biased Normals should have a decent write up in the Tech Ref.

It is my understanding that Biased Normals is still the default.

[robcat2075]

An A:M patch will display only one normal to give us a clue as to how it is facing. However every point on a surface has its own unique normal that is calculated at render time to control, for example, how the light hitting it shades it.

[thefreshestever]

wow! this IS big!!! makes everything silky smooth THANKS!

[robcat2075]

I wonder why 50% is not the default.

 

Can anyone contrive a case where 50% is bad?

[Gerry]

My head hurts, but in a good way.

[Fuchur]

I wonder why 50% is not the default.

 

Can anyone contrive a case where 50% is bad?

 

Maybe with a 5-pointer and flipped normals?

And try a hook too... had bad luck with those situations.

 

See you

*Fuchur*

[thefreshestever]

i´ve tried it on a few characters, all have five pointers and hooks... worked fine. maybe it´s not the default because it´s someting that has to be calculated and can slow things down on a complex character?