Day 49

The previous post Day 47 and 48 has been updated, a new walkthrough of normalization rather.

Mr Douglas got ready the camera angles and dragon animation for us to follow.

Introductory Shot

Flood Shot

Dragon Flood Sequence

There were few additions to the terrain we've thought of adding.
However with the vopsop rock generator, that would be an easy task.

As for the rock generation digital asset, I still have one last problem to solve. That is allowing the user to visualize the geometry being repositioned to fit the bounding box, which I still can't manage to figure out how to do.

Day 47 & 48


Here's a walkthrough of a method which enables user to:
1) Import a low-poly geometry.
2) Tweak the geometry in 3 different sections of the geometry regardless of shape and size.
3) Apply a layer of vopsop as shown in previous walkthrough. (See day 40)
4) Render bgeo.

Special thanks to Mr Ron for cracking his brains over this method. I could have never come up with all the expressions myself without his help.


==========================================================================



Import in a low-poly base mesh and subdivide it. Don't subdivide it too much or you'll face PC crashing based consequences later.

Create 3 transform nodes to act as the following functions:

1) Rotate geometry about it's pivot to fit bounding boxes which are meant to capture top, middle and bottom points of geometry. Rotation will be defined by user.

2) Center to centralize geometry and zero out transformations.

3) Normalize geometry to fit into the scale of 1 unit for bounding boxes to act upon.

Create 3 bounding box groups to control the top, middle and bottom of the geometry. The bounding boxes will grab certain points of the geometry (based on where it's position) so that transform nodes can be applied to edit those parts.

Expressions used:

bbox("../xform_center", D_YSIZE)/3

In the Y channel of Size attribute. This expression controls the size of a bounding box. It divides the scale in Y axis by 3 according to the geometry. Thus this allows all 3 bounding boxes to fit into the 1 unit the geometry is confined to.

centroid("../xform_center", D_Y) - or + bbox("../xform_center", D_YSIZE)/3

In the Y channel of center attribute. This expression is used to position a bounding box right in the middle of the geometry. Subtract or add the previous expression to position the bounding box bottom or top.

centroid("../xform_center", D_Y) + bbox("../xform_center", D_YSIZE)/3

centroid("../xform_center", D_Y)

centroid("../xform_center", D_Y) - bbox("../xform_center", D_YSIZE)/3

Create 3 softTransform nodes, each softTransform node will control the points of the geometry within a bounding box by reading a group name.

The softTransform nodes will be for the user to twist the geometry and make the rock more organic looking.

Create 3 more transform nodes. These will be used to reverse the rotate, center and normalize nodes. The edited geometry will then be transformed back into its original scale and position.

Reverse Normalization

Reverse Centralization

Reverse Rotation

Add a pre-generated vopsop layer onto the geometry for additional rock details.

Here would be a good time to increase subdivisions slowly to see extra details pop up.

==========================================================================

This section of screen shots shows how a user will use this rock generator before I turn it into a digital asset.

Day 46

Here's the 2 expressions I was talking about in my previous post.

Today I've spent most of the time testing pyro simulations as I'm once again stuck with the rock generation. I can't seem to reverse the normalisation in it.

I shall ask Mr Douglas and Mr Ron for assistance in the review.

There are also some problems I'm facing with pyro fx and I'm currently still figuring out how to successfully produce a secondary simulation. I hope I can solve all my problems by friday...

Here are some test simulations

The first thing I want to create is a nice looking mushroom cloud with fire continuously burning into the clouds.

nuke_testRender02 is the result of me adjusting curves in the fuel and smoke amount graph.

The fire continues to burn but the smoke doesn't react.

nuke_testRender03 is a more successful look but the fuel and smoke dies away after some time, in this case I dragged the keyframes close to their default positions.

Here's the thread in odforce containing my w.i.p and request for help:
http://forums.odforce.net/index.php?/topic/13196-nuclear-explosion/

Day 45

No work screen shots for today as it's quite unnecessary. What I mostly did was solve normalisation problems using expressions and gain more understandings and knowledge regarding pyro fx.

I had a couple of questions for Mr Ron, most of which involved me being stuck at some point in both the rock generation and pyro fx area.

Here's a summary of the FAQ session:

What expressions do I use if I want 3 bounding boxes to control a geometry?

bbox("../xform_center",D_YSIZE)/3

Assuming the geometry is already scaled down to 1 unit using the expression mentioned 2 posts ago (1/$SIZEX), the expression above controls the size of one of the bounding boxes. It divides the scale in y axis by 3 according to the geometry. Reason being I want to have 3 bounding boxes altogether (top, middle, bottom).

centroid("../xform_center",D_Y) - or + previous expression

This expression is used to position one of the bounding boxes. Use the expression centroid("../xform_center",D_Y) in center y to position the bounding box right in the middle of the geometry. Subtract or add the previous expression bbox("../xform_center",D_YSIZE)/3 to position the bounding box top or bottom.


Pyro fx questions:

"pyrosolver/sources/emitters/fuel amount(dont forget to scope the channel and adjust the curves)"?
Shift click channel to open graph window. Alt left click to create keyframe. Adjust the curves to your liking.

Prolong smoke emission?
Adjust curves as explained in previous answer.

Control intensity of fire within smoke? (See Russian Tsar Bomba Reference)
Control pyro surface shader in shop network. Play with the curves to achieve wanted looks.

Ideas on how to emit glowy effect from nuclear upon explosion?
Refer to previous answer above.

Pyrofields caching?
A good time to cache the bgeo files is when the simulation time takes about 10 seconds per frame.

Should I use the advanced tab when working with pyro fx?
Nope, next time buddy.

Day 43 & 44


Here are my storyboard ideas, I've finally scanned and uploaded them.

First Idea :

Second Idea :

Mr Ron! The pyro fx videos you provided were great! Now I understand much of the basics of pyro. Well there's too much to describe what I've learnt so far but here's some screen shots of some simple tests and renders I've done so far. I'll put up more descriptions in the future once I've familiarized myself with pyro fx and when I'm fluent with it.

 

From here, I tried forming the shape of a nuclear mushroom explosion.

Before that I've encountered a slight problem when resizing the fluid bounding box simultaneously along with the simulation of the explosion, it just couldn't work. In the end I realized it was due to a typo error I made.

Over the weekends Mr Douglas came up with a test file involving the use of bounding groups and softtransforms. I've tried applying the similar technique to the rock generation but I seem to have run into a little bit of trouble. I'll ask Mr Douglas or Mr Ron for help regarding this matter. It should get fixed by tomorrow.

Day 42

During the review with Mr Douglas and Mr Ron, thanks to them, several new ideas came up on how much more improvements we can apply to the rock generation digital asset.

Here are some improvements to be made:

1) Apply twist and softtransform to the geometry to give the rock a more organic look. (Instead of being uniformed and straight all the time.)

2) Use bounding box groups and apply deformations to several sections of the rock geometry. Apply simple expressions on the x, y and z axises to fit the whole geometry within 1 unit, apply the bounding boxes, then bring the edited geometry back to original scale.

3) Setup a rig using bones.

4) Create a parameter which allows user to export out the generated rock as obj.

There's always room for more ideas but these are what we have so far.

So I've been working on those new ideas.

Mr Douglas showed me how to proceed with idea number 2. However I'm stuck at the point where I'm supposed to use the expressions. I don't know if this is correct: 1/SIZEX 1/SIZEY 1/SIZEZ in the x,y,z channels. It does cook up the geometry but no changes are made. That's why I think something's wrong with the expressions...

Okay I've just called Mr Douglas and I've corrected my careless mistake. There's a $ in front of SIZEX. So it's supposed to be 1/$SIZEX 1/$SIZEY 1/$SIZEZ.

Here's the result. It's a start but I'll maximize the usage soon enough.

Day 41

At about midnight I've suddenly realized something about the rock generation.

I had issues before, regarding the use of my own modelled base meshes and applying vopsop on it.

The way to counter this problem is really simple, I wish I had seen through this earlier.

First, I just created a cube in maya with a few subdivisions (I made it as simple as possible). As you can see it's just a simple arc-shaped polygon. All I did was move a few vertices here and there and it's done. After that I exported the geometry out as obj format.

Next, I imported the low-poly arc geometry into houdini, subdivided it and plugged it into the vopsop which I had prepared earlier (See day 40 for my vopsop walkthrough). With that I got an arc-shaped looking rock. It's not perfect yet but it's a start.

The main idea is to get the right amount of subdivisions for the base geometry no matter what shape it is. I try to make the low-poly meshes with as few subdivisions as possible. After that I'll increase the subdivisions using the subdivide node in houdini.

Here I'm just doing some test renders using the default stone shader provided in houdini.

I've also played around with setting up the overall terrain. It's a test first as I'm not ready with the rock generation digital asset yet.

The setting up has been going pretty fast and easy as everything is procedural. Reason is because I've installed the height map terrain digital asset and I have the rock generation vopsop node. If any changes need to be made I just need to rely on those 2 controls.

At the same time I've done a number of simple test renders.