Hi there… I came across an issue - don’t know if it’s a bug or what, but when moving between HD sculpting and regular sculpting, the HD details are get softened with the transitions, resulting in a loss of detail. It’s a very small amount of detail being lost - very fine details that don’t go very deep into the mesh are being softened out or eliminated. Example: use an alpha to etch a design very lightly in HD sculpt mode (so you can see it, but barely), then move out to regular sculpting, then back into HD sculpting. Back in HD sculpting, the original level of detail has been lost for a softer version. Is there any way to prevent this from happening? I’d like my finer details to remain intact - as sculpted.
Hey Robb,
This is simply because standard subdivisions cannot support the vast number of polygons available in HD sculpting, so when you switch back from HD ZBrush will do the best job it can to display your fine detail but will just not look the same. If you want to see the full sculpt in HD there is a render function for that.
I’m just speculating here, but we are told that Z5 will be 64bit so one can assume that even finer details can be achieved without having to use HD mode (due to the greater amount of RAM the software has access to).
Hope this explains things.
EDIT: Sorry man, just realised thats not what you meant. I hope someone else can clear this up!
I think this must be a limitation in ZB. Ideally you should be able to switch between HD and standard subdivisions without losing detail but it just doesn’t work this way. Perhaps HD sculpting is designed as a last step for ultra high frequency details after you have finished with the rest of your work.
Like I said, hopefully this issue will be adressed with ZB5.
Thanks for the answer Trist… it’s a bummer because I thought the whole purpose of HD sculpting was to create new subdivisions (as if regular subdividing), but to limit sculpting/painting access to one segment of a model at a time due to high poly count… so as to not overwhelm memory AND potentially processing power available… sooo… I guess I expected that it wouldn’t be any different than creating new regular subdivisions in terms of model structure. I guess that’s not the case. That’s a bummer… big time… I just lost a day’s worth of work adding fingerprints to my sculpt that are almost completely missing now. 
(I know that’s unnecessarily detailed for a full body sculpt, but this is my first sculpt and one of the purposes is to learn ZB better, including HD sculpting.)
I just got off the phone with Pixologic, and was informed by the very nice gentleman on the other end that this was an issue the development team is aware of. As such, I decided to do some follow up to help them fix this - hopefully in time for 4R2b!
I created a sphere, made it Polymesh3D and subdivided up to 4th level, then created 2 subdivisions of HD geometry. In HD sculpting mode, I drew some very fine lines (using a crease brush I created to emulate the crease brush in Sculptris) that were faint but clearly visible, and exited and entered HD sculpting mode. EACH TIME I reentered HD sculpting mode, I noticed that the fine details were further dimished with each and every pass. Eventually the fine line was all but gone.
I also tested saving the tool file in HD and non HD sculpt mode, and the file size in HD sculpt mode was considerably larger. When exiting HD sculpting and then resaving, the file size resumed it’s smaller size.
At first I thought that perhaps the data was being changed as part of the process of computing the effect HD sculpting had on the “standard” subdivision level geometry (which is important too of course), but it seems logical to me that information would take effect on the lower subdivision levels only, and not have any impact on the HD geometry at all. (There would be no point in changing it.) Coming from a developer’s perspective and background, and given that not all HD information is lost (only softened, or “averaged”) it seems to me that the code is trying to condense the HD geometry information during the process of leaving HD sculpt mode… presumably to make storage as efficient as possible.
If this is true, then perhaps the data is being compressed in a lossy fashion, rather than lossless. (I don’t know for sure as I’m not on the development team - I only wish lol) Using lossy compression is very efficient for memory and disk space, true enough… but if this is the case, then the cost is too great IMO. I don’t think any artist here would wish to sacrifice the integrity of their sculpting data (potentially compromising their art) in exchange for efficiency in memory and disk space utilization. Memory and hard disk space is cheap. Losing information, however subtle, is far more costly, imo.
Of course, I’m guessing on the how and why at this point, but my assumptions seem reasonable to me, given what I do know and not having seen any of ZBrush’s code. I’m hope I’m on the money!
OK, nuff said… I hope the development team gets a peek at this thread. I’d love to hear their thoughts on this.
Good for you for taking the initiative to call Pixologic on this one.
I do hope someone notices this thread, its a pretty substantial glitch that affects the work flow of many an artist, especially those of us still leraning.
If you want to be sure this issue is addressed, just submit a ticket with Pixologic. I have done so with other issues in the past and have found the team to be very open minded and receptive to the ideas of people in the ZBrush community.
Anyway good luck on your first sculpt, I hope those fingerprints aren’t too difficult to reproduce!
