IRender can place a Background Image behind your model.
The new Background Wizard , introduced in Version 4.0, make it easy to position your rendered model in a background, and to remember the settings for future renderings.
To invoke the new Background Wizard select Preview/Position from the Background Tab.
- Background Positioning - slide or resize background image.
- Distortion - distort background image to adjust for Perspective or rotations.
- Save or Copy - save or copy the resultant image directly from the rendering without re-rendering.
Watch the Video: Background Wizard Video
- See: Background Wizard
The Background Tab is used to define background image and also for Ground Plane materials.
- Click Browse to select an image to use for the background.
- Click Clear to clear the background image.
- Visible - image is visible (will override any sky settings)
- Reflected - image is reflected in windows.
- This determines how the image is projected onto the sky of background.
Create Planar HDRi Image
- Converts a normal image to a HDRi background image.
- See: Planar HDRi Backgrounds
- Clear out Background Image
- Select HDRi Image from disk
Offsets and Scales
- Use the Image Layer Wizard to size and position the background image and set these values.
- for Cylindrical and Spherical Projections.
Maintain Aspect Ratio
- if this is not checked, the background image is stretched to fill the screen.
Adjust Center Line to Horizon
- If checked then the image will be scaled and offset so that the horizontal center line of the image matches the horizon of the current perspective view.
- The image is scaled and positioned so that it still fills the entire background of the rendered image.
- See: Horizon
- Resets Offsets, Scales and Rotation.
- Loads the Background Wizard to easily position and scale the background image.
- See: Background Image for examples.
- On - turns on the Ground Plane
- Alpha Channel - makes the ground plane transparent, but shows the shadows on the ground.
See: Alpha Channel
- Elevation - set the elevation of the ground plane.
- See: Ground Plane
Ground Plane Material
- From the Background Tab you can define and edit materials for the Ground Plane.
This lets you apply a grass texture for land, or a Procedural Bump Map and reflection to emulate water.
- See: Background Tab
Alpha Transparent Ground Plane
- With an Alpha Transparent Ground Plane, you can save the rendering as an Alpha Transparent image, and the ground plane will be transparent. However, shadows on the ground will be visible. This can be used to place the ground plane image on top of a background image and still see where the shadows would appear. (Of course this works best if you are placing he image on a flat surface.)
Visible and Reflected
This shows samples of the 4 possibilities for Background visible, and Background reflected.
A non-sky image has been used for the background, because it make it easier to wee when it is visible and when it is reflected.
These determine how the image is projected onto the sky of background.
Here are some examples using the same sky background and 3 different projections.
Notice that the cylindrical and spherical projections stretch out the image more to fill the entire background. This may work properly with normal sky images, or you may need a 360 degree image to stretch around the cylinder or sphere.
Scales and Offsets
Here are some examples of scale and offset for Backgrounds.
If you check Adjust Center Line to Horizon, then the image will be scaled and offset so that the vertical centerline of the image matches the horizon of the current perspective view. If you have created your background image with the horizon in the center, then this provides a more realistic view - especially when seen through windows.
Planar HDRi backgrounds
You can use a, (non panoramic), HDRi image as a background.
To use this feature, select Browse on the Background tab and choose a .HDR file.
You can create a Planar HDRi from a normal image using the Convert Image to HDRi background button on the Background Setup Tab.
Settings for Inverse Tone Mapping
Tone mapping, (converting from HDRi to normal images), takes luminance and creates RGB colors for display or saving in an image. Inverse tone mapping reverses that equation. nXt's tone operator requires two other pieces of information in order to invert it properly-- the average luminance and the maximum luminance of a scene. The way it works at the moment is that you select Daylight, Nighttime to get default values, and then adjust the custom settings for Average and Maximum illumination in the image.
Lumens and Default Values
After selecting a normal, ("Tone Mapped"), image, you can set the Average Lumens and maximum Lumens which control how bright the image will appear.
- Daylight 5,000 and 20,000
- Nighttime 1 and 500
Load this image as a Planar HDRi Background
After converting your image, you can load it as a HDRi background for rendering.
If you use a Planar HDRi background with the Path Tracer , you can adjust its brightness as an additional lighting channel after rendering.
HDRi Image Adjustment are not working with the standard renderer yet from the Rendering Window. However, you can save the rendered image in Native Image format and use the HDRi background channel (8) in the
nXt Image Editor