Improving formZ RenderZone Plus Rendering times

-- Improving RenderZone Rendering Performance: Why does my file render so slowly?

Hardware: Rendering Speed is controlled by the speed of the processor. The faster the processor, the faster the rendering. If you do not have enough RAM, this will force your computer to use Virtual Memory, which will slow you down with OS X, and slow you down a lot with Windows. If you will regularly be working with a file of this size, you should consider adding more RAM. The video card will only affect the Wire Frame and Interactive Shaded displays, and will not have any effect on rendering speed.

Shadow Maps: One frequent cause of insufficient memory is too many, or too high resolution shadow maps. See the SHADOW MAP MEMORY FAQ for further details.

Geometry: The more geometry that is contained in your scene, the longer it will take to render and the more memory it will require. In general you should only model what you will see. For example, if you are working for a hardware manufacturer and making a presentation model of a doorknob, you can model all the details, curves, keyhole, etc. But if you are making a model of a subdivision, you should create extremely simple doorknobs (if any), and you should never use the "presentation doorknob" in a "subdivision model" -- even if you have it handy from a previous job, or found it somewhere on a web site. Inspect your polygons. If an object looks like it is shaded in a Wire Frame display, then most likely its resolution is too high and it should be modified or recreated.

Surface Styles: The more Surface Style effects you select, the more time it will take to render. Therefore, if you are concerned about rendering speed, you should only select the options that you will need. You can also get an idea of how complex a Surface Style is by watching how long it takes to draw the small preview of the Surface Style Icon. (Changing the preview to Sphere will take a little longer to draw the preview -- thus giving you a better relative idea of its complexity. The type of preview icon will not have any affect on the time it takes to render objects with this Surface Style.) You should also generally avoid "double transparencies." See the GLASS SURFACE STYLES FAQ for further details.

Rendering Options: The more Rendering Options you select, the more time it will take to render. The main option to avoid (if possible) is Super Sampling. See the SUPER SAMPLING FAQ for further details.

Lighting: Advanced Lighting effects such as Atmospheric Lighting, Area or Line Lights, Accurate Glow, and Environment Lights will add (perhaps considerable) time to your renderings. Use the Basic Lighting suggestions from the LIGHTING FAQ for fastest results, and see the other tips for optimizing more advanced lighting.

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-- Glass Surface Styles:

Glass Reflections should generally not be used with another type of Transparency, as this creates a "double transparency" which will take considerably longer to calculate.

The Glass Reflection includes a Refraction coefficient which controls how light will bend as it passes through a material. Thus this surface style should only be used for Solid objects, and not Surfaces or Surface Solids (since these do not have any thickness through which the light can bend).

Because Glass Reflections Refract the light, they are not included in an Alpha Channel Background (because you can't "bend" something that is not there at the time of the rendering). If you want to use an Alpha Channel Background and do not need Refraction, you can use a Mirror Reflection combined with a Simple Transparency, and then these transparent objects will be included in an Alpha Channel Background.

Transparent Shadows can be generated so that light will pass through glass materials based on the Transparency / Transmission factors. Transparent Shadows are set in the Shadows section of the Light Parameters (which can be accessed by double-clicking on the light from within the Lights Palette.)

Transparent Shadows will also pick up the color of the transparent material so, for example, the colors of a stained glass window could be projected onto a wall or the floor. Transparent Shadows do take a bit more time to calculate, so another option might be to select the glass objects and turn off the Attribute: Casts Shadows. This will allow light to come through your windows without extra calculation times.

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-- Moire Patterns: Why do I sometimes get radial patterns in my images -- especially when viewing a Grid or a Brick Surface Style in Perspective?

Moire patterns can occur when there is insufficient resolution to show the necessary detail in a perspective image. The easiest / quickest way to fix / improve this is to Edit the Surface Style that is responsible for the Moire Pattern (usually a Grid or Brick shader), click the Color (or other) Options, and check the Area Sample Option.

If this does not sufficiently resolve the problem, the next best solution would be to render at a higher resolution. If you can not increase the resolution of the rendering (ie, you are generating an image for the Web, or an Animation), see the section on SUPER SAMPLING.

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-- Super Sampling: This is a rendering effect that can be used to reduce or eliminate Aliasing or Moire Patterns. To achieve this, the image is rendered at 2, 3, or 4 times the specified resolution (for Low, Medium, or High Super Sampling), and then sampled down to the desired resolution. Because rendering at 2, 3, or 4 times the resolution generates 4, 9, or 16 times the number of pixels, the rendering times will also increase up to 4, 9, or 16 times when using Low, Med, or High Super Sampling.

Super Sampling can also be accomplished manually, by rendering at the higher resolution, and then reducing the resolution of the final image by exactly 2, 3, or 4 times. This option may be desirable because in this way you will be able to use the higher resolution image as well, if you like. For example, you could generate a high resolution rendering for print, and then manually Super Sample it to generate a high quality / lower resolution image for a web site.

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-- Soft Shadows: Why can't I see my soft shadows, or why are they so fuzzy or rough?

Soft shadows utilize Shadow Maps to create the soft edges. In certain conditions the shadow map resolution can be too low, which can result in the pixels of the shadow map being visible, or in extreme cases, it can cause the shadow to disappear altogether. (Think of zooming in really close into a low resolution image.) To solve this issue, you need to know a little more about how shadow maps work:

By default, the size of a Shadow Map is the smallest bounding box that encompasses all of the objects that cast shadows. And by default the shadow map resolution is equal to the resolution of your renderings (which you specify via Image Options from the Display Menu). If your view contains all of the objects that cast shadows, then you should not have a problem with shadow map resolution, but as you zoom into your scene you are effectively zooming into your shadow map.

Most often users encounter problems with shadow map resolution when they introduce a large ground plane into their scene. To remedy this situation, simply Query the Attributes of the ground plane and set its Casts Shadows Attribute to Off. (Leave Receives Shadows ON so that it will still receive shadows from the other objects in your scene.) If you would like to change this (or many other attributes) for multiple objects simultaneously, you can do this with the Set Attributes Tool.

If turning off the Shadow Casting Attribute for the ground plane (and outlying objects) is not enough, then you can also change the Quality of the Soft Shadow to High. In extreme cases you may also need to increase the resolution of the Shadow Map or limit its extents from the Shadow Map Options. Edit your light and click the Map Options button from the middle of the Light Parameters Dialog. Here you can increase or decrease the resolution of the shadow map. Note that doubling the "Times Image Size" number will quadruple the memory requirements for this light, which will be displayed at the bottom of this dialog. You can also use the Limit Map: option to constrain the size of the map to All Objects (default) or All Completely Visible Faces or Objects. The smaller the size of the map, the less resolution you will need to get the same quality shadow, but note that limiting the map may cause shadows to be dropped from objects or faces that are not completely in the scene.

Hard Raytraced shadows do not have this limitation, and will always produce shadows with crisp edges.

See the SHADOW MAP MEMORY FAQ for further details.

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-- Shadow Map Memory: Why do I get an Insufficient Memory message for Shadow Maps message?

Shadow Maps Memory requirements are determined by the size and resolution of the shadow maps, and by the types of lights that are casting shadows. If you Edit your Light Parameters and click on Map Options, you can see and control how much memory your Shadow Maps will use. By default this will be set to 1 times Image Size. Thus as you increase the resolution of your image (from the Display Menu/ Image Options), the memory requirements for your shadow maps will also increase. If you double the resolution of your image, it will double both the X and Y size of your Shadow Map, and thus this will require 4 times more memory for the Shadow Maps. Alternately, if you enter 0.5 or 0.7 times Image Size in the Shadow Map Options, you will use one quarter, or one half the amount of memory, respectively. The resulting memory requirements for each light will be shown at the bottom of the Shadow Map Options dialog.

Thus, to check how much memory your shadow maps will require, first set your desired image resolution, and then multiply the memory requirements for one light by the number of lights that are casting soft shadows. Note also that Point Lights will cast shadows in 6 directions, and thus will require 6 times more memory than distant or cone lights. If you do not have enough memory for this, you can either reduce the number of lights that are casting soft shadows, use cone lights instead of point lights to cast the shadows, or reduce the resolution of the shadow maps.

formZ version 5.0 and later will automatically detect when you do not have enough for full resolution shadow maps and give you the option to automatically reduce their resolution.

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Also, if you are rendering with Global Illumination, these threads from our Forum should help:

Rendering Questions: http://www.formz.com/forum2/messages/16/26981.html?1209078321

Interior Rendering: http://www.formz.com/forum2/messages/16/27092.html?1209731347

Dome Lighting: http://www.formz.com/forum2/messages/16/26647.html

Lighting and Rendering: http://www.formz.com/forum2/messages/142/27028.html?1209402936



Of course, it is still worth looking at the FAQ's for other good tips...

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