KirstenLee S21(3) Released Review

KirstenLee Viewer S21

KirstenLee S21 Logo

Today KirstenLee has released the first complete version of S21… well… one that is not a release candidate. I’ve been enjoying using the Release Candidate 2 version for several days. I’m happy to see this version out. My impressions of the viewer follow.


The install program shows the version as, which shows the viewer is using the newest possible code from Linden Lab, who’s Development viewer is at 2-6-0-219259. The ‘3’ is KirstenLee’s development iteration as 219259 is the Lab’s. The Lab is averaging 68 iterations per day, which is pretty impressive. I suspect KirstenLee has far more iterations than the version numbers show.

The install download is 28mb. The prior S21 RC has to be uninstalled prior to installing S21(3), which is typical for KirstenLee’s  S2x series. Install is straight forward.


This version has the Favorites at login feature. It is off by default. Turn it on in Me -> Preferences -> Privacy  and check Show my Favorite Landmarks at Login… Once on and provided you have used the sidebar Landmarks panel to move some Landmarks into Favorites, you will find the favorites list in the Start At box at login.

In the article KirstenLee S21(3) RC2 Review I went through the settings. I don’t see changes (I may just be missing them – I don’t think so…), so I won’t redo them again here.

The install, even though it does an uninstall, remembers your settings. If you want a totally clean install, do a separate uninstall and manually remove any leftover files before starting your install.


Having just looked at the SLV2.6 Development version I noticed the order in which things rezzed in the Dance Island shopping area. I think S21 did a better job of rezzing nearby things. However, distant objects in my line of site were rendering ahead of nearby objects and textures.

Once the gazillion textures downloaded I was getting 8 FPS. That is with Lighting and Shadows, Ambient Occlusion, and Sun/Moon Shadows. Turning off Sun/Moon and rebooting the computer got me up to 18 to 21 FPS.

User Interface

In the previous release candidate KirstenLee reverted the viewer back to more of a SLV2 style user interface. The S21 viewer is now compatible with the Starlight skins.

I’ve written in other threads about the problem of deviating from the SLV2 user interface. Since all the new SL people are starting out with the SLV2 interface, changing to another user interface creates an obstacle to new people using the viewer. It will be interesting to see what TPV’s do with the user interface in the coming months. I suspect we will see user interfaces evolve into a basic SLV2 style with various neat TPV add-ons. Time will tell.

Whatever the case, S21 now has 8 skins installed and is the UI is more SLV2 like.

Remember. The viewer and skins are changing so fast they are unlikely to work well. If you want the most stable and trouble free viewer stick with the default skin. I found using the Azur skin, while really pretty, has transparency problems. Opening lots of windows reveals the problem. Some window do not go opaque when selected, which makes using them difficult.


Taking JPG pictures were extremely slow in the RC. That has been fixed in S21(3). But some of the options that were so nice are gone. One can only save Colors or Depth now. Matte is gone.

Depth of Field

In the RC this was a pain. In S21(3) DoF is basically turned off by default, my preference. You can read about controlling the affect of DoF in the previous review; KirstenLee S21(3) RC2 Viewer Review. This image is from the previous article, it shows the DoF effect.

Depth of Field

Exaggerated DoF

Render Pipeline

S21 has the newer pipeline by Runitai Linden with modifications by KirstenLee to suite the purposes of the S21 viewer.

Memory management in this viewer has moved over to TCmalloc. This is pretty geeky stuff. Suffice to say it should reduce memory leaks and improve performance. KirstenLee has modified the TCmalloc used in S21 to be more aggressive in releasing memory. Kirsten also provided the SL TCmalloc version to allow users to change between versions.

I’m not sure how one changes from one version to the other. I see some files in the Program Files -> Kirstens S21 folder. The files are probably libtcmalloc_minimal.dll, libtcmalloc_minimal(safe).dll and I’m not sure which is file is which, I’m assuming the (safe) is the Linden file.

Two versions of OpenJPEG are provided. The default is probably the safer of the two. The alternative is faster but not as compatible. If you are asking what using a less compatible version might do, the answer is; it is hard to say. In many cases it completely depends on the specific image/texture being processed. If an incompatible skin texture fails in the OpenJPEG tube the avatar may fail to rez or it may appear funny looking. Also exactly what will happen when image processes fail is also hard to predict.

The in use OpenJPEG is openjpeg.dll. The alternate is: openjpeg (2.0.4 faster Rename me to use).dll. If you change them, be sure you save the original so you can change back.

Multiple Processes

KirstenLee and Altair are looking at doing more with OpenMP in future S21 versions. (Wikipedia) You may be aware that the SLV is more or less a single process and does not take advantage of multiple CPU cores, at least not as well as is possible. OpenMP is a step in the direction of allowing the viewer software to do more parallel processing. To the ‘I’m not a geek’ peeps this just means it is another way to make the viewer faster and use more of the features in new computers.

Video Card Support

The viewer now has support for many of the new video cards people likely got for Christmas. Both nVidia and ATI cards have been added.

Mesh Support

S20 supported mesh rendering. So does S21. But not mesh uploading.

The problem is somewhat like the image/texture upload process Linden Lab uses. No matter what type of image you upload it gets converted to JPEG2000. LL uses KDU a proprietary library for handling those images. TPV’s use OpenJPEG and introduce some incompatibilities. It is up to the TPV Devs to work those problems out. Something similar is in play with mesh.

One of the big hang ups in the upload process is creating the simplified object Havok uses to calculate collisions. LL uses Havok to figure out and build the object, which is then uploaded with the mesh. Users don’t really see the object, but it is referred to in the mesh upload dialog and the user has some control over it. But, the Havok process means a resident is not FORCED to create the simplified object Havok needs.

The TPV segment is not able to use the Havok processes to make mesh up loadable unless they license Havok. Havok is not open source. So, those sections of code have been unavailable to TPV Developers. The TPV Devs were having to develop some alternate method to handle creation of the simplified object, which is often referred to as a convex hull or bounding box depending on the context of the conversation.

Apparently the Lab is making much of the SL Havok related code available to TPV Devs. This lets them see what the Lab is doing and build something similar. Hopefully that will speed up the process of getting mesh upload in TPV’s. This is a big thing for the OpenSim people… like me.

The Problem and the Benefit

Appearance Problems

Appearance Problems

In SL this is just an awesome viewer. But, I also use the viewer a lot in OSGrid, I have 4 regions there. Several of my Myst-Uru role play friends are there too. With the RC 2 version I’ve had persistent problems with my clothes and appearance. I would be wearing 2 skins and not rezzing or wearing a load of clothes from previous logins. Wearing another skin would correct the rez but not remove the other two skins. S21(3) doesn’t have the rez problem but it is showing a load of broken links in the WORN view. As the image shows, I am wearing multiple eyes, bald, and skin and no way to detach/take off.

S21 is targeted at SL. So, I’m not surprised that it is not completely OpenSim compatible. OS has some catching up to do. Other than the appearance thing, which is minor, there is the TP blocked by attachment state. OS is having lots of tp problems, but the messed up appearance thing is not helping. That problem seems to have gone away with this release. I can once again zip across region boundaries. And zip is the right adjective. Region crossing is much nicer today. Whether this is the viewer or OSGrid changed something I can’t tell. After a lot of crossing I got logged off OSGrid. …must be a fun limiter in the grid… 🙁


Kirsten’s S21 is a high-tech bleeding edge viewer, which Kirsten describes as being in perpetual Beta. If you are a photographer or machinima maker this is the viewer for you. It allows you to get the dramatic images now seen in other viewers.

I used the S21 RC to get some images of my building in OSGrid. I like lots of lights for dramatic effect. S21 renders those and makes for some nice images. The build is certainly not that great, so the viewer helps a lot.

Leave a Reply

Your email address will not be published. Required fields are marked *