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The goal is to provide an overview of topics that may come up when working with HD-Addons and Subdivision levels in DAZ Studio.

Just jump to those sections which are of interest to you...

Updated 2017-07-13: Updated example images that show how to figure out the proper SubD level for which the morph was created

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@ Understanding the difference between HD-Addon morphs and maps and their usage

The basics:

HD morph:

High Resolution. Used for objects clearly visible in the foreground of your image.
Accurate physically calculated shadows are cast, works great with Physically based rendering (PBR).
For the best result dial in exactly the same (render) SubDivision level for the morph as it was created for.
You can improve system performance by adjusting the (render) subdivision to a lower level but then you will see less detail.
Allows export of the model as .obj . at the highest SubD level to use or render in 3rd party software.

Displacement map

High Resolution. Used for objects clearly visible in the foreground of your image
Accurate physically calculated shadows are cast. Looks great in PBR but you need to set it up properly.
There are different types of displacement, more advanced ones like vector displacement are not yet supported by DS or Iray
There are different types of maps (0 = black or mid grey). Render engines feature adjustment sliders to make use of all of them

Bump map

Low resolution. Used for objects in the background of the image
Simulated simplified shadows can be detected in directional light situations. (clothing structure may look fake etc)
Versatile: Bump maps can be added to the displacement slot and with the help of adjustment sliders look great also in BPR

Normal map

Low resolution. Used for objects in the background of the image
Simulated simplified shadows can be detected in directional light situations. (clothing structure may look fake etc)
There are different types of normal maps designed by different software for different render engines.
Render engines may not feature sliders to quickly adjust normal maps.

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@ Mixing HD Add-ons with existing maps

Question:
Is it wrong to use maps in combination with HD? Or are you supposed to use one or the other?

- In theory when you create details for a model in a 3rd party software you catch all details together by exporting to the one map type or morph type you prefer.
In theory artists could provide all different map types as separate presets in their products so the customers can choose the one that bests fits the current need.
In practice artists have a history of mixing different map types for different types of detail.

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- In theory HD morphs could be a replacement to use instead of other maps.
In practice HD morphs are often used to add some other type of details as well to be used in combination with existing maps.

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Commentary:
Detailed product descriptions could help to answer how the product with an HD-addon is intended to be used:
- are HD morphs supposed to be a replacement or an "add-on" to the existing maps?
- what type of detail is provided with what type of morph or map?
- which subdivision level is needed to see the morph at the highest quality?
- are different preset types for each object included?
Example: One high resolution preset to use the model in the foreground One low resolution preset to use the model in the background

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@ SubDivision levels vs Render SubD levels

The Render SubD level raises the SubDivision level only in the calculations by the (Iray) render engine in the final render window. The SubDivision level of the object in the DAZ Studio scene is not affected.

Example G8F:
Set Render Subdivision level to 3
Set Subdivision level at 0

This means a scene object can have only 16'000 points (vertices) in the DAZ Studio scene but is calculated and displayed as a 1'000'000 points (vertices) object in the final render window.
-> You raise the Render SubD level to see HD morph effects during rendering without slowing down DAZ Studio scene manipulation.

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Raising the SubDivision level will also raise the actual point count of the object in the scene.
- You need to raise the Subdivision level if you want to see the effect of HD Add-ons in the openGL or Iray Preview viewport drawing styles that are not able to support Render SubD.
- You need to raise the SubDivision level if you want to export models with HD Add-ons to 3rd party software.
- You need to raise the SubDivision level if you want to see the HD morphs visible in 3rd party render engines like Octane.

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@ Understanding the difference between SubDivision levels

Basically if you subdivide a mesh you add addtional points without changing the position of the allready existing ones.
Each new subdivision level will increase the point count by multiplying it by ~ 4x depending on the shape of the faces (tris, quads)

en.wikipedia.org/wiki/Subdivis…

Note that different software may count the subdivision levels differently.

DAZ Studio calls the base resolution SubD level 0.
In ZBrush the base resolution is called SDiv level 1.
Make sure to always indicate the software when talking about subdivision levels.
The difference in the actual point count increases drastically on higher levels:

In practice this means:
If a HD morph is sculpted for the Subdivision level 3 you need to dial in the same Subdivision level 3 in order to see the morph. If you dial in lower subdivision levels you will only be able to observe the very rough changes to the mesh but not the finer details. The difference between SubD 2 and SubD 3 is ~ 800'000 points that are not being displayed on the lower level!

Another example:
If micro level details like pores would be created at subdivision level 4 it is crucial to dial in the morph at subdivision level 4 as well. If you would dial in the lower subdivision level 3 the difference would now be ~ 3'000'000 points that are not being displayed.

-> It is crucial to know the SubDivision level for which the morph was created!

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Commentary:
It might help both existing and new users if HD morph sliders would include Subdivision level information
Example:
Charactername - Bodypart - HD - SubDivision level
Eva 8 Head HD SubD 3
Adam 8 Body HD SubD 3
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@ checking the point (vertex) count of an object when dialing in subdivision levels

You can use the Scene Info tab to show how much points (vertices) an object has when dialing in actual subdivision levels.
Example
Genesis 8 Female
SubDivision level 0
16556 Points (Vertices)

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Genesis 8 Female
SubDivision level 1
65'806 Points (Vertices)

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Genesis 8 Female
SubDivision level 2
262'514 Points (Vertices)

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Genesis 8 Female
SubDivision level 3
1'048'762 Points (Vertices)

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Genesis 8 Female
SubDivision level 4
4'192'568 Points (Vertices)

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@ Difference between Base Resolution and High Resolution

Question:
Is there anything else that needs to be changed to activate HD?

There is a toggle between Base Resolution and High Resolution.
Base Resolution does override the value set of both the Subdivision and Render Subdivision level!

At Base Resolution the model is displayed at its lowest available point (vertex) count.
At High Resolution the values set at Subdivision and Render Subdivision level will be used.
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Example:
Cube
High Resolution
SubD Level at 4
has 153'602 points (vertices)

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Cube
Base Resolution
SubD Level at 4
has 602 points (vertices)
-> The SubD and Render SubD levels are ignored.

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-> Make sure the toggle is at High Resolution to see HD morphs.
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@ SubDivision level limits

If you want to change the SubDivision levels you may notice that sometimes you can not go higher then a set limit.
The intention of setting a SubD limit may be that users do not accidentally raise the slider to a higher value that may freeze or crash DAZ Studio.

Remember: Raising the SubD level raises the point count of the model by multiplying it by ~ 4x.

If you do want to raise the SubD level past the limit you can do so by clicking on the Parameter Settings "wheel" icon next to the parameter that you want to adjust.

Example:
If you want to create some microlevel detail pores for Genesis 8 Female SubD 3 with 1'048'762 Points may not be enough.
-> Raise the limit to SubD level 4 before exporting your .obj
4'192'568 Points should be enough to sculpt and create high resolution diffuse and displacement maps.

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Warning: (Status 2017)

On a system with an 8 core i7 processor with 64 GB RAM a Genesis Female 8 at SubD 4 is manageable.
However save your scene before trying out if you can raise the SubD level past the limits.
Raise the SubD level only one at a time when trying out the limits for your personal computer.
After raising the SubD level check if the viewport is still responsive to scene manipulations.
Check the base resolution point (vertice) count before raising subdivision levels past the limits.
If the model has a high base resolution even SubD 2 or 3 could crash DAZ Studio.

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@ Subdivision Algorithms and their smoothing effect

Question:
Why do objects have rounder edges when raising the subdivision levels?

Many subdivision algorithms like the default "Catmark" also apply a smoothing effect to edges and corners.
If you want to keep hard edges on objects like a cube use the Biliniar Subdivision Algorithm in combination with the "Sharp Edges" Edge Interpolation.

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@ Finding out the proper Subdivision level for the morph

If there is no information in the product description it is mostly trial and error to find the proper level when you dial in a HD morph with sliders from the shaping tab.
If you do load a complete character HD-Addon or object from presets then in most cases it seems the Render SubD level is set at the proper value.

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Test Setup for HD-Addon characters:

- use a 3 point light setup

example:

www.daz3d.com/boss-pro-light-s…

(Do not use HDRI backgrounds for portraits if you are interested in seeing accurate micro level detail shadows)

- zoom the camera in on the face with focal lenght of 100+

- remove the diffuse map on the face and lip surfaces

- remove any bump, normal or displacement maps on the face and lip surfaces

-> Now you should have a default gray skin with visible shadows cast by the 3 point light setup

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-> Note: Raising the Render SubD level has no effect on the Nvidia Iray Live Preview !

Iray Preview - SubDivision Level 1 - Render SubD Level 1:

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Iray Preview - SubDivision Level 1 - Render SubD Level 5:

-> This means you will not see any difference in the Nvidia Iray Preview viewport when you change the Render SubD Level slider.

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@ Checking HD morph details in the Nvidia Iray Preview viewport

If you are using the Nvidia Iray Preview viewport you need to raise the SubDivision level by one level to check if you can see a difference.
Repeat this until you can not anymore notice any improvement.

Iray Preview - SubDivision Level 2:

It can help to have the Scene Info tab open to get an idea about how the point (vertex) count raises when increasing SubDivision Levels.

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Iray Preview - SubDivision Level 3:

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Iray Preview - SubDivision Level 4:

Note: In order to dial in SubD Level 4 you may need to raise the limit to 4 as described before.

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Iray Preview - SubDivision Level 5:

Warning: Dialling in Subdivision Level 5 raises the point (vertex) count to ~ 17'000'000.

Nevertheless, you cannot see any more improvement in the micro level details.

-> It can be assumed that the morph was created for Subdivision Level 4. There is no point in dialling in a higher Subdivision Level than that.

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@ Checking HD morph details in the in the Final Render Window

Of course you can also compare the difference in details by using the Final Render Window.

If you are using the Nvidia Iray Final Render Window you can just raise the Render SubD levels by one level to check if you can see a difference.

You can keep the Subdivision level at 1. In that case the Render SubD levels will be applied only during the final render in the separate window.
Keep increasing the Render SubD levels until you can not anymore notice any improvement.

Iray Final - SubDivision Level 1 - Render SubD Level 1

When the Final Render Window is open you can also check the Geometry Memory Consumption in the separate Render Log Window.

-> Geometry Memory Consumption at Render SubD 1 is ~ 3.7MB (~68'000 vertices)

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Iray Final - SubDivision Level 1 - Render SubD Level 4

-> Geometry Memory Consumption at Render SubD 4 is ~ 231MB (~ 4'000'000 vertices)

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In the very first years HD-Addons may have been created for DAZ Studio SubDivision level 3. (~1'000'000 vertices)
Newer DAZ Original characters with HD Addons seem to be created for SubDivision level 4. (~ 4'000'000 vertices)
If there is no official information provided you may need to try out yourselves for which level the morph was created.

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