Thursday, August 25, 2011

Xnormal - Normal Maps


You should do piece by piece baking (and combine the result in Photoshop later on).
*Tip - when baking Normal Map in Xnormal - change the background for the nromal map from purple to black, and in AO - from white to red, so its ALOT more easy to select with one click of magic wand later on PS.
One thing to consider, the hole process of normal map baking is combination of topology, uvs, geometry similarity, normal angles, xnormal settings and its all a mess if you have no idea how to do it.

- Good idea is always to check normals before exporting low poly OBJ. Select your model piece - DISPLAY - Polygons - Face normals, to check in which directions normals are going.
- A quick way to flip the normals would be to use "Conform" which will make all of the normals face the same direction and then you can flip them all together. Then you can use average normals to get them to even out over the surface.
- If normal bakes look ugly (messed up) - try to Unlock Normals in Maya and resave lowpoly obj model for re-bake.

Sometimes you can use the "use exported normals" in Xnormal (on low poly setting).
Edit your low poly model in Maya - if you see DARK EDGES after applying Normals - Smooth Edges - correct with -> Vertex Normal Edit Tool (under normals Menu). Export your obj and bake with "use exported normals" / you may also re-bake with "average normals" and compare the results.

There is a set distance calculator you can use in Xnormal. Tools - Ray Distance calculator (unfortunatelly that never works for me - even I played with those - it never gave me the desired results.).
- I DON'T know if thats true, but i noticed on my normal map renders that Scale Mesh 1 / Ray 0.1 = Scale Mesh 5 / Ray 0.5 = Scale Mesh 10 / Ray 1 all those settings give me the same result.
my theory>>>>>
 - removing small artifacts on bakes - use 0.1 (smaller number)
- 0.1 - rays casting distance - very close
- 1 - rays casting distance - broad (far)
- also depends on Scale Mesh - for the ray casting - but always use SAME Scale Mesh for Default Mesh Scale and Mesh Scale BOTH on low poly and hi poly, then play with different Ray castings.


Two ways to make a cage
1. Using Xnormal 3D Viewer
2. Using your software program (Maya, Max) to make a cage and export it as additional .obj
(To manually add an external cage in Xnormal - on your low poly - check Use Cage, the under "external cage file" right click - choose "Browse external cage", you may also reset external cage from right click menu, using cage also overrides the Rays settings, even thoug they are shown).

Export obj. then open Xnormals and load the low res and high rez piece.
Click on the "3D Viewer button." Once inside you will see at the near top left of the viewer - there is a "Show Cage" button which will show the cage for your low res mesh. Once you click that, it brings up a few options of which one is a slider called external cage. You can then use the "expand cage" slider to make it bigger, basically you want it to encompass the model piece entirely. You can also edit small points manually by selecting the "Edit Cage" button and then selecting verts with the middle mouse button and using the x, y, and z sliders. When you are happy with what you have click "Save Mesh" and save it where you want it to and then click yes to have xNormal load the maps for you. Go to the low poly meshes and make sure next to the rays that the "Use Cage" checkbox is selected. Then check your setting and bake.
3D Viewer is great because you dont have to manually create cages in maya and it saves off separate meshes. The only trick you may have to watch out for, is if you ever want to use the cage meshes again, make sure to click "use cage" in the low poly settings in xnormal. This should give you much cleaner bakes!
- AWSD - are the keys to navigate in 3D Viewer. Right click button also rotates around the camera. Its a little annoying to navigate, just use combination of AWSD and right click.
- When you edit the cage - yous elect the verts with MID mouse button. Use sliders for global or X, Y, Z to move the selected vert.
- Why you have to load the high poly (as far as i know) - because the cage HAS to be OVER the high poly (othewise you get artifacts) - so the cage has to completely over -hug the high poly.
- To exit temporalily without closing 3d Viewer - hit Windows button on keyboard (if you hit ESC it will CLOSE the 3d Viewer). To go back in side ALT + ENTER.
- once you click Save Mesh and YES it EXCHANGES the high poly and low poly (and saves that separately in SBM file) so its save, you can always go back to your previous meshes!
- you have to click USE cage, BUT Xnormal does that auto after you exit 3dViewer.

One thing to consider while doing external cage in Maya - is never to exctrude faces (or duplicate faces) because it changes the vertex ID and the WILL NOT work in Xnormal. TOPOLOGY HAS to be the same as the low poly and it has to be simply - scale it, move a couple of faces/ edges/ vertexes around and thats it. ( in Max there is a push modifier and it just works differently than maya plus you can export various file types).
- GREAT trick to INFLATE in Maya is >>> Select model > hit W for move tool, change setting to "move normal" - grab N handle and drag back and forth along the vert normal to the distance you prefer.
- To Inflate a cage out of original low poly. make a copy of the low poly - select the verts -> Edit Mesh -> Transform Component - drag arrow and it inflates it for you.

In Maya - you can only export the .OBJ so it works in Xnormal.

Another trick i use is ... for very complicated close-together parts - in Maya I selected a couple of faces and duplicated those tough sections - like small piece - re-bake those SEPARATELY in Xnormal and copy pasted the normal map (parts) in PS.
A link to tutorial Zbrush:

Monday, August 22, 2011

Retopology - Maya or Topogun

Some great free videos and tutorials from CGBOOTCAMP at:

Great tutorial/explanation on Bad Geometry (Maya):

*Tips if you come FROM ZBRUSH. Depending on your model, it may have lot of subtools and lot of polys. Try to decimate your model in Zbrush, so its not that high on millions of poly / OR lower the SDIV in Z then export as obj. Topogun (as Maya) cannot handle millions of polys like Zbrush, so have something in a range that is manageable.
Export .obj a couple of ways:
Under Decimation Master - Export (make sure all your subtools are visible) - this will create all 1 meshed .obj file fom all the decimated subtools.
Under Subtool Master - Export. Chosse settings and export - it WILL export all your subtools separately.
click on the subtool you want to export (in Tools Menu on top under Save as) - Export.
*Tip - if you need to merge a couple of subtools - make those visible, click Merge Visible - it will make a NEW subtool with merged ones.

Import your hirez object/model into TG. File - Load reference.
Importing multiple obj's in Topogun:
-in Zbrush merge the part without merging verts and then export it as a obj. The obj will store the multiple object when exporting and in topogun each polygroup will be assign to a group.
-in Maya - select all parts of model and Export Selection.
In TopoGun:
you can "load a reference" .obj that contains multiple objects (called groups) and toggle object (group) display off/on independently for retopo. (On top area of TG there is a button "group" - click it and a menu will pop up showing all different subtools).

Exporting the newly created rtopo ->> File - Save scene as - choose the extention .obj when saving the scene.
Importing back the retopo to TG ->> File - Load Scene - choose .obj retopo

Tools Menu:
Simple Edit - use to make selections, marquee, etc. (HOT KEY - with Right CLick you change between SimpleEdit and SimpleCreate tools). Left Mouse - selects - choose in Tool  Options: by verticles, edges, faces, or all of them.

SimpleCreate - put down vertices, edges on top of your reference. Click somewhere in the reference it creates a starting point/vert. SHIFT - splits edges (or ads a vert)
When you turn on "Make Faces" feature - it makes auto faces when clicking.

Draw - a topology brush that you draw topo you want
Bridge - to bridge edge loops

Left-Mouse button to lay down ac ouple of vertices, it creates edges between them -
CTRL - connecting something
SHIFT - splitting something

SUBD - button on top - makes an "adaptive skin" or shows a preview of your smoothed retopo mesh.
Subdivision Parameters - you can change the settings for seeing SubDiv in TG. If you have Project turned on, you can also see (depending on Levels) - the projected skin from the reference onto your new mesh.
You can save the Subdivision mesh and export .obj for sculpting further. From Subdivision Parameters - choose desired SubD Levels, MOD or ZTL, the Subdivision ->> Save.


Making a NURBS tube shape out of 2 curves
Go to an orthographic view (side or front), it's easier to work on orthographic with curves.
Use the CV curve tool (or EP curve tool) to make a curve. Create a NURBS Circle, no matter where. Select the circle, holding SHIFT select the curve. (SURFACE MENU) Choose Surfaces - Extrude. For options, pick Tube, At Path, Component, and Profile Normal. Choose Extrude.
After that, you can select the circle and scale the circle to see that the path will follow.
Now converting NURBS to Poly
In the menu Modify > Convert> Chose Nurbs to Poly Option Box>>
The images shows MY options that I prefer when converting Nurbs objects to Polygons.
-Quads, General, U type / Number U (are the number of edges that are going to be created on the U axis), V type / Number V (are the number of edges that are going to be created in the V axis).

Sunday, August 14, 2011

Zbrush Alphas


Working with Alphas:
If you want to apply an alpha (I usually choose Standard Brush - may also duplicate the brush), choose DragRect, choose the alpha and apply (left mouse click and drag til the desired position). Playing with Zadd, Zsub, Z Intensity value you may tweak the result.

Importing Alpha:
Alphas are black to white images, you may prepare your alpha in Photshop, save as .bmp .psd .jpg .gif .png .tiff .tga (the supported formats), in Zbrush - click Alpha - Import. (I think one donwside of Zbrush is when you re-work your alpha, you have to import it again and that does not overwrite your previous version, just adds the newly imported alpha - i think its a pain, ending up with several "same" looking alphas" in the thumbnail preview window).

To be able to move an alpha when applying to model surface
hit "G" (for Projection Master) - choose Deformation and Normalized (checked only) - the Color and Material are NOT checked, Drop Now. Apply your alpha, when moving it choose move, rotate tools, when you are done hit "G" again and choose "PickupNow".

On a brush choose an alpha, go to menu Alpha - press "Make St" - a transparent square appears. To be able to activate and work with it hold SPACEBAR (Zbrush 4 or right click Zbrush 3). You can move, scale and rotate the alpha. Then choose Alpha Off and with a desired brush draw over the sqaure to get the result. Go to Stencil Menu and turn the Stencil off.

Choose Document Menu - size 256x256 and Resize.
Get Plane3D, draw on canvas and choose Make PolyMesh3D (in tools menu button). Then choose that tool and Edit. Divide a couple of times the rectange (Geometry - Divide - make sure you turn OFF Smooth (smt) ).
Draw some shapes with the brushes and when you are done, go to Alpha menu - GrabDoc.

To make alpha tilable.
Draw some shapes on canvas ( on polyMesh3D divided), make sure do not cross/ exit the rectangle. When you are ready to make it tileable - Turn EDIT off (by clicking it), choose "S" SIGN - for Simple Brush, hold down TILDA "~" and drag>>> this makes the alpha tileable, as going to tile the canvas and this goes for all directions. When you are done, get out of edit mode (if you are), select "S" SimpleBrush and go grab the Mrgbzgrabber (what this thing does is grabs a depth map from your canvas and saves a black and white image in your texture panel). Click and drag outside canvas and this is gonna make an alpha for you. Then click on your Alpha Menu, select that alpha and Export it (as well you can manipulate it in PS, then import back to Z).

For custom alphas (or any other too), in order to NOT show edges around square of the edge of texture - got Alpha Menu - and play with values of the MIDVALUE and RF.
*Tip - if the image/alpha has medium grey edge, use MidValue to tweak the results. RF is for radial blur the (edges) of the texture/alpha.

Using Alpha (from texture file).
Go to texture panel, apply texture (texture ON under Tools Menu - Texture map), (Tools Menu - Maskin) mask by intensity - make sure you are in the highest divisions, so you get the most of the detail of your texture, then turn your texture OFF.
* tip - CTRL + Click on the mask will blur it. Alt + Click on mask will sharpen it.
You can either take a brush and start sculpting over the mask. Or go to Deformation Tab and Inflate, it will get a basic inflation of everything.

Creating an Alpha from Mask.
If you dont have your subtool UVed and you draw a mask, which now you want to create an ALPHA from:
Go to UV master (your model needs to be on SDiv 1 - the lowest). In UV Master (which is in Plugins - if you dont have it - find the plugin in Zbrush official website and install), click Unwrap (TO preview your Uvs in Zbrush - click under UV master menu - Flatten, to close the preview and go back to 3d model - click Unflatten.).
Go to Masking (under Tool menu) - click Create Alpha. Yu can now export it from Alpha Menu. It saves a 16 bit, Grey (no Rgb) image. Use .PSD format for easy tweaking in PS.

Displacement map is a texture map, so you need UVs to make one.
Put a texture map with texture you wanna displace (import the map file before that). Under Tool menu - Texture Map - New texture, chose it - Texture ON. Open Displacement map chose the same map BUT imported as ALPHA. Turn Displacement ON, slide intensity you can see the poping up of detail from displacement map, to see it applied you have to click Apply. Go to Texture Map and turn texture off. Its a good idea before applying displacement map to have Layer on recorder mode.

Zbrush Brushes

Brushes have different Type, Stroke and Alpha.

Brushes are located in 2 different folders
Pixologic >> Zbrush 4.0 >> Zbrushes
Pixologic >> Zbrush 4.0 >> Zdata >> BrushPresets (I use this folder for custom created brushes).
.ZBP is the brush extention.

- PRESS S to change brush size
- PRESS B on keyboard to get brushes menu
- Change BRUSH MOD (modifier) - if positive will push out, if negative will push in.

Make sure you have high enough level of subdivision on your model in order for the brushes to have smooth and nice appearence.

General Settings - Mrgb, Rgb (applies color) (rgb intensity values), Zadd ( usually raise the surface - pulling out), Zsub (usually lower the surface - pushing in), Zintensity - how strong the bush is applied, Focal Shift (makes the inner circle of the brush bigger of smaller - harder or softer applying), Draw size - how big the bush is.

BRUSH TYPES ( Each brush has a unique behavior)

Standard - standard brush if left as default applies soft nice curves when you draw. STANDARD BRUSH - if modifier is 100 - pinch, if modifier -100 Mushroom the mesh for mass and muscles.
Smooth - usually when you press SHIFT by default settings.

Clay - very organic feel
Flaten - flattens the surface
Layer - some more flatten resault
Morph - you have to press Morph target first to get that brush to work. (In Tools Menu - Morph Target >> Store MT). Draw soemthing on your model, select Morph brush and using intensity and settings, it brings back the original model (deletes what you draw after morph target on the model).
Move - move the pieces of geometry, great for reshaping
Move Topological
MOVE brush - turn on Acucurve

Pinch - pulls the geo in.
TrimDinamic - for hard surfaces


Each brush has STROKE feature (stroke is a separate menu in Zbrush)
Drag Rect - great for applying alphas - one alpha per drag.
Freehand -
Spray Stroke - sprays the alphas.
Spray Color - sprays the alpha in more transparent way.
Drag Dot - drags a dot of alpha.

LazyMouse - follows the move of your mouse more precisely, evening the stroke, dependig on settings.
Insert CurveTube
SliceCurve - separate in polygroups
SNakeHOOK brush!!

insertCylinder with SYMERTY (radial)
HOLDING ALT while INSERTBRUSH (then ctrl drag) will make a hole. holding spacebar while draging InsertBrush will move it whiole draging. holding SHIFT while drag - scaling it.

to make BRICK details on Geo - PUT TEXTURE (with bricks), MASK by intensity , USE LAYER BRUSH!

draw lines - perpendicular to make topology
Hold ALT to delete a curve
HOld close to  a green dot, see red line to continue curve
Curve modifiers (in stroke) - Curve snap distance

Hold SHIFT to make round curve line across object

Stroke - curve functions - Smooth

Have your brush on DOTS for stroke. Go to Stroke Menu - Turn on Lazy Mouse, play with Lazy Step values, Lazy Radius 1, Lazy Smooth 0. Basically the Lazy Step is the stroke spacing in Zbrush 4. (at least of what i know.. will update if any other method come up).
ON most brushes under Stroke "Spacing" will not be available..

BIG MODIFICATIONS on low level, FINE detail on HIGH level

Sculpting folds:
Standard,  change Curve AccuCurve ON, Depth, graviti strenght - higher value, more gravity on brush. Stroke - Lazy Mouse ON - Lazy step lower value - 0.02. Dots, Lazy Radius 1.
Brush Modifier - 30,

COLORING in Zbrush:
Standart brush - duplicate - take off lazy mouse - STROKE - RGB ONLY
Start from this base
C= pick upo color
V = switches the color
COLOR SPRAY - STROKE - modifiers - color variations (0 makes the same color)
under BRUSH >> Alpha and Texture - POLYPAINT MODE - 1 - Standart, 2 - Colorize, 3 - Multiply, 4 - Lighten, 5 - Darken

To export a texture from polypaint >>>
Tool Texture Map - New Txtr
Tool Texture Map - Create - New from Polypaint.
Then Clone texture (click the texture IMAGE - export)


Saturday, August 13, 2011

Zbrush Basic - General

If you draw a lot of object by mistake on canvas. Go edit (selects the last one drawn) click on FRAME (button on Right side, or predss F), go Layer and Clear.
OR CTRL + N for new document, that clears everything on canvas.

Document menu:
Saving the document WILL NOT save your 3d work (or Ztool).
The background gradient of the canvas is controlled by (Document Menu) Back, Border, Border2.
Change color - click on "Back", choose a color from color picker.
"Range" changes the "gradient" of the canvas. Get rid of the gradient - set to 0.
Increase the level of gradient with "Center".
"Rate" is how fast does the gradient change.
To change the size of document, make sure you remove your 3d model first.
WHEN importing multi object - FIRST import the largest part, thats how Zbrush handles scaling. Then choose the largest object and in subtools - append the rest of them.

GRID:  Draw: Grid Size (change). ALso FLOOR has button selections for X, Y and Z.

If the normals are the opposite from Maya to Zbrush - select the object with inverted normals, go to DISPLAY PROPERTIES in Tools menu - click on FLIP.

- PRESS CTRL over a button to get INFO for it.
- Turn LOCAL On - RHside "local" THE PIVOT POINT - the last point I click becomes the pivot point
- Geometry DIVIDE - go up on res level press D; go down press Shift D
- To be able to see inside the model - in tools on bottom DISPLAY PROPERTIES - Click
and activate DOUBLE
- For more accurate selection >> use POINT SELECT ON >> in Transform menu
- MASKING - CTRL ALT - to sharpen the mask, CTRL to soften the mask
- Remove material information - go to Flat color and prezz Zadd and M, fill object.
- Smoothing Divide - if you turn SMT off, it will divide but edges will be still the
- to SubDivide a particular area on your model, MASK off the part you dont want subdivided - be sure to be on the LOWEST SDIV level, hit Divide.
- Press SHIFT + F - to show polygroups and wireframe.
POLYGROUPS (in tools)
autogroups - will separate all subtools (separate objects)
uv groups - separate by UVS
GROUP VISIBLE - separate by selection
(to select polygroups - Ctrl + Shift + Click
Make polygroup out of masking shortcut: Paint A MASK - hit CTRL + W = make polygroup out of the mask (from visible)

At first may seem abit strange and hard to make it work, but once you understand it - its great.
BE SURE to store MORPH target on the HIGHEST subdivision level you are on! See the image - this appears in the morph menu when youhave a morph target stored.\
*TIP - always a good idea after you stored the MT, to use Layers when sculpting
IF by any chance you have stored MT on lets say Sub-div 3 and youhave already sculpted some details on the model, or on layers, and now you decided you need to go a level up to SubDiv 4. Duplicate your subtool, delete all the sculpting (layers) or use MORPH brush to erase all detail! Now you should have a original subtool with detail and duplicated subtool with NO detail. On duplicate delete  the morh target, go level UP and Store again MT. Now start projecting the settings from original one by one to the duplicate!

If we are going to export from Zbrush model back to Maya - is NOT a good idea to do
a GROUP SPLIT (from zbrush)

GOZ is little tricky and often going back and forth between Zbrush and Maya should be with extra care! Save Often (and make new ZTL files in case something got skrewed you can always go back to a previous state!).
*To clear the clipboard of Zbrush - exit Edit mode, CTRL + N - cleans the canvas area, click the BIG S (SimpleBrush) icon under Tools, choose your model again draw on canvas ENTER EDIT mode.

If you have a problem is with the X symmetry, like trying to sculpt something but you notice that the symmetry is not even. You need to mask out the half of the character you're happy with
and then go to Tools>>>Deformation tab and find Smart ReSym - it should fix the problem. It copies the masked half across.

SUBTOOL MASTER - organizes different objects exported from Maya into Subtools in Zbrush
TRANSPOSE - manipulate multiple objects inside Zbrush. In edit mode of object - move, scale ot rotate - click on of those. Draw an action line - We got 3 different point to manipulate.
MOVE SELECTED - Click on center wide dot - reposition the model. Click outside red dots - Scale or sheer the model. Center of the dots - does the action, moves the object towards the other end of 3 dots. If we click the EDGE of dots will reposition action line.
SCALE SELECTED - center dot = scales along the axes, perpendiculat to action line end dots scale towards the other side.
ROTATE - use thes as a lever.

Mirroring OBJECTS with Subtool Master.
When you have your subtool and want it mirrored (on X) for example a shoe, make sure you have your layers baked in, before mirroring (because it will encounter problem).

Group will split polygroups into separate pieces
Blur smooth out the mesh
POLISH - great - polishes geo (LIKE creasing edges)
Project - keeps the detail as is
ADD geo in Zbrush - mask, hold CTRL + move.

Remesh can be very useful but sometimes a pain to do.
Make sure your low poly mesh (geo) is all equal and nicely even quads. Close all holes and gaps, because remesh and projecting in general in Zbrush do not like any cavities. Also WHEN PROJECTING - make sure your faces are NOT overlapping, and normals are flipped the right way.
Import your low poly model (one piece and should NOT be complex!!), the pieces of your model have to be logically separated, do not remesh a complex whole mesh, better separate in Maya and close all the gaps. You can remesh as many subtools as you want.
Divide the model a couple of times (do not exceed subdivision 4, 5 or 6 - depending on polys and complexity). Choose a higher resolution for better remeshing (by default is 128), choose a value for Polishing (default is 10). Remesh all.
After the piece is remeshed - divide it a couple of times so it matches his master. With both subtools VISIBLE, click project all.

HOW TO UV a remesh.
This task can be a little tricky - due to the high poly content of the remeshed tools sometimes.
Lets say you have a piece (subtool) on SDiv 5, that needs to be remeshed.
* Does the new remesh carry the same UVS as its master? When you do REMESH - it comes WITHOUT UVS.
So how do we do Uv on a remesh? Fisrt off - for a BIG heavy original piece that needs to be remeshed - use low remesh settings, make sure the new remesh is accurate to the original, otherwise you dont want holes and gaps in your new remesh.
Also note that UV master CANNOT handle LOTS of polys!
So with the newly created (kinda low poly) remesh, use UV master to unwrap. If you get an error doing unwrapping in Uv master, i think that your remesh has to be lowered on polys.
I do this 2 ways:
1. Either change settings for resolution when you create the remesh.
2. Or bring in Maya and:
- LOWER polys (Polygons - MESH - REDUCE) - bring back to Z.
- you can also make quads faces (remesh in Z used triangles as well as quads) Mesh - Quadrangulate, so when you bring back in Z - also check if under Tools - Geometry - Reconstruct SubDiv.
*Tip about UV Master, you can use existing UVs from imported model and work on that in UV Master - just click "Use existing UV Seams" button before you hit "Unwrap".

Making Uvs for a human head.
Open UV master - Zplugin - UV Master
Symmetry ON (if the head is symmetrical),  Enable Control Painting (ON, it will lit in color orange).
Click the button Attract - and start painting WHERE you want your seems to be. Make sure the blue line color of your paint is connected (for the seems).
Click Protect - start painting (red color) the FACE, so it protects the face from being cut on seems.
Click Unwrap. To check the Uvs - Click the button Flatten. You MUST be on the lowest subdivision level for that feature to function.
To go back in 3d view in Zbrush - click Unflatten.

How to RENDER:
When you have a model you want to render, go Document and change width and height -  make the size of the desired render. This will clear your canvas, so drag your model again, hit Edit. In Zoom Menu hit AA Half so you have Antialiasing. Click Render Menu and hit Best.
You can Document> Export image as .psd, .bmp or .tiff or PrintScreen.
* Step by Step How to:
Open you model in Zbrush - applpy material. Go to Document size and make it double as much as you wanna render - lets say 4000px x 3000px. Clear your canvas (CTRL + N) drag your model, press T to do to Edit mode. On the upper right corner ise ZOOM button to pose your model inside boundaries of document. Then click Actual (for actual size) then CLICK AAHALF - that turs anti-aliasing on. Open render Menu, make sure buttons Shadows and AOcclusion are ON. CLick BEST (for render), wait for image to render and dont click anywhere else (it will exit the rendering mode) - click Document - export and export your image in one of the 3 formats - .psd, .bmp or .tiff.

Decimation Master is used to create a model with lower polycount while still keeping most of the details. It's vey easy to use. Its a plugin you have to install separatelly in Zbrush (but its free). Its located under Plugin Menu - decimation master. When using Decimation, sometimes you dont really see anything happening (of course depending on settings), so to see difference Hit PolyFrame (Shift + F). What is actually does is automatically reducing your mesh.
If you have multiple subtools you can choose from the following:
Pre-process current - processing the current tool you are on
Pre-process all - processing the whole tool
Then choose either:
process % percentage
process K polys (you can assign any number of final result here)
Process K Points.
Once you choose the decimation quality you may:
Decimate current (for current subtool you are on)
Decimate all - for the whole tool.
*Another trick is - if you are on a subtool, you can mask off the desired areas which you want decimation to retain resolution (try to mask with LOWER intensity of color, so its more transparent) - then pre-process current, then decimate current. Its gonna tell Zbrush to kind of retain the geometry in this area.
* Good tip - when you decimate all your subtools - you can do all in one or separately one by one.. but in the end - click EXPORT button - it will export all your subtools as .obj file.

SPOTLIGHT 0 is located in the texture menu.
Open TEXTURE menu (on the top) drag it on one of the sides. Import an image. There are some buttons right under the images  (the spotlight buttons) the 4th one from left to right - with a + and - sign on it. That loads the image you have selected into the spotlight. To TURNO off the spotlight with hotkeys - press SHIFT and Z. To show the spotlight circle press "Z" for on and off. (Z key to bring up the Spotlight control wheel).
You can also SAVE the spotlight and load it.