I have been asked several times if I could give tips on what I do to reduce land impact when uploading my mesh. As a result, I figured I'd jot down a few tips and tricks I use when I want my mesh to look good, but not bog down Second Life servers, cost me an arm and a leg to upload, as well as not look like something that comes from your worst nightmare. Please keep in mind, most of this tutorial covers all aspects of mesh creation that I could think of, including just exporting a mesh out of Mesh Studio or your viewer and optimizing it in Blender.
This is a work in progress so please bear with me.
* Size DOES matter here...it really does!
So when you upload a model you carefully and painstakingly created, you need to remember size matters. The bigger your model is, the more it is going to cost in land impact. While this is not necessarily true for all mesh, ie: you have a big wall but the LI is only 5 and a nice earring you made has a land impact of 15. What I do mean is that if you make that wall or earring bigger or smaller, it will change the LI for the servers .
Below is an example of a happy Holidays Sign I made for my Christmas Snow Globe I give away:
Uploading this mesh costs the servers 6 in land impact but when it is sized down:
The size is now 1.5 meters and costs the servers 6 in Land impact. I know this is basic and you probably all know this, but it is important to keep this in mind when you are uploading your meshes because the detail and size of your mesh is going to influence the land impact. BUT there are ways we can upload you mesh and not only keep the mesh's details, but keep your mesh from going crazy in high land impact as you will see later in this article.
* Keep in mind the four degrees of Level of Detail or LOD
Remember you have four levels of detail that you need to consider when uploading your model. The first one is from your model's file that you are uploading, the second is medium, then low followed by the lowest setting. These settings are important when you consider how people are going to see you mesh in-world.
This is what a shelf looks like without messing with the LOD the land impact is .529. While this might not seem much, changing the the medium, low and lowest to this:
You will now get a land impact of .500. The shelf alone will register as 1 prim/LI, but when you link it to another shelf in-world, you will get a lower land impact overall:
As you can see, the shelves linked equal only 1 LI. If we had kept the setting we had when we uploaded, we probably would have had 2 or more.
Another though on uploading you mesh and messing with the LOD aka Level of Detail, is when you upload, keep in mind how people will see your finished product. For this project, we don' need to worry about people seein these shelves from a very far away, so the distortion at the lowest and low levels is not an issue. If you making a building however, you would want to play with the setting more to get the proper balance between low distortion and low land impact.
* Remove all sides of your builds you don't see
When I build objects in second life, it is mainly because I want to make sure I have my dimensions perfect for my potential users. Most of the time it would be easier for most people to just build it in Blender and import into Second Life, but not me. I am a bit OCD in this respect so I just use either Mesh Studio, PrimGenerator or just build then export out of my viewer.
When I save my items for export, I go to all edges that will not be seen and set them to 100% transparency like this:
I then export out of my viewer and make sure that transparent faces are skipped, like this:
That way, when I go into blender I see this:
This way, I don't need to go in and delete hidden faces one by one in blender. All I need to do is join the mesh and do whatever I need to for finalizing my mesh.
If I have the time I will just model my mesh in Blender, that way I know I have gotten rid of all hidden and unwanted vertices and only have a lean. Mean, well designed mesh for my users and customers.
* When you import into Blender, remove all double vertices.
I cannot stress this enough. This will build you land count up faster than you can say “Bob's your uncle.”
To do this:
Go into Edit mode and click on the “Tools” tab in the toolbar and go down to the “Remove Doubles” button and click it:
You should then see your vertices and edges in the top of the Blender window decrease:
This can save you a lot of time and effort as well as cut down on your land impact for your object. This is also important when using tools sucj as Mesh Stuio, Prim Generator, or the export from a viewer.
* If your have sculpties or a mesh that has to many polys, consider using a re-topology tool.
I will sometimes convert my sculpts to mesh or even have a mesh that just has way to many polys and I need to reduces them. CGcookie has a WONDERFUL re-topology tool that can be found here. This can be used for cylindrical objects and they will soon have polystrips to take care of the rest. What these tools do is to remake meshes such as your old sculpties and create new meshes with less vertices and more manageability. While these products come with a price tag ($35), you can still use the old standby and re-topologize your meshes by hand in Blender then by using the shrink-wrap modifier or Bsurface and some other tools included in Blender. To see how it's done, there is a good tutorial here, although it is a bit old. (I might have to create a new tutorial on how to do this in 2.73) :-)
* Use your Decimate modifier, it is your friend.
I use the decimate modifier as often as I can. I will however, warn you to use it as your last step just before you are ready to upload your model and also save a copy of your model before you use the modifier as it can sometimes break your mesh. Also, be aware that you will probably have to re-bake your ambient occlusion map as decimate can also break this as well.
With that in mind here is how I use it:
When I am done with my mesh and I get ready to export it I click on the modifier button and add decimate:
As you can see, the ratio right now is at 1.000, we will want to lower it to at least 50%. This is just where I start and go lower until I see distortions. At that point, I will go up about 10 to 15 percentages higher just to make sure I look good in world:
* Make sure your physics fit the model. Aka....Don't go crazy with a physics model your build doesn't need.
Physics are so hard to deal with, well, I guess they aren't but at first, it can be a lot to get your head around. One thing to remember that physics can be your friend, and in the same breath your enemy. Physics an either lower or raise your land impact depending on how you use them, and uploading them properly into Second Life can sometimes end up being a headache.
In this case, simple is always better. For that matter, so is lower. I try to keep my physics shapes as simple as possible and use the lowest setting that is appropriate for my build. In this case, I am using a window
There are a few good tutorials out there that cover this subject in more depth. One by Elenora Newell that can be found here on youtube or one by Elout De Kok/Cel Edman here and you should take a look at them as they will go into more detail than I did. I may add a tutorial and mesh physics later, but for now, I hope this article helps with your mesh projects.