Как сделать скайбокс в блендере
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The light coming from the sky is often one of the primary light sources. In Blender terminology, we rarely hear the word skybox. Instead, we use phrases like world material or environment, but they are all the same thing.
To set up a sky texture, go to the world material tab, expand the surface section and press the yellow dot next to color. Choose sky texture from the list. For Eevee, change the sky type from Nishita to Hosek/Wilkie or Preetham as Nishita isn’t supported in Eevee.
In the rest of this article we look at adding a sky texture through the node editor, how to configure it and animate it. We will also briefly cover adding an hdri image as an option.
How do I use the Sky texture in Blender?
In the introduction we looked at how to quickly add a sky texture to light our scene through the properties panel. The interface in the properties panel has the same data as the node editor. only presented in a different way. Normally, we use the node editor instead, since it gives us much more control and a better overview.
To set up the sky texture in Blender’s node editor, follow these steps:
If we don’t want to use the node editor we can use the properties panel to setup a sky texture as well, just like we did in the introduction. Follow these steps:
It is a different interface, but the result is the same.
I would encourage you to use the node editor since that is what you will use most of the time if you dive into learning how to set up and use materials.
Sky texture settings
We have three kinds of sky textures.
Each of these are mathematically generated sky textures that use different algorithms. Each type has it’s own settings we can use to change the look of the sky.
Nishita sky texture settings
Nishita is the only sky texture that only has numerical parameters. The other kinds have a vector input we change by draging the interface to change the position of the sun. While these vectors can be animated, Nishita is easier and more precise.
The Nishita sky texture has no inputs. We can control the parameters by using drivers but not with other shader inputs.
The first setting is Sun Disc. This toggles the direct sunlight on or off. Effectively also removing Sun size and Sun intensity. But we can still use sun elevation and sun rotation. The result is an overcast sky eliminating any sharp shadows from the sun.
While the sun disc is active, the sun size will soften the shadows the bigger the value, while the intensity will intensify the contrast between light and shadow. So if you don’t want to turn off the sun direct light completely, you can increase the size and decrease the intensity for a softer look. Something that is often desirable.
The rotation and elevation control the sun position in the sky by rotating it and adjusting the height. This also have an effect on the color of the rest of the sky.
The rest of the parameters have to do with the atmosphere rather than the sun itself. The altitude changes how high above the earth surface our scene is perceived to be.
With a higher altitude value we go from a warm indirect light to a much cooler blue indirect light from the atmosphere, just like if we were approaching space and the ground has less of an effect.
Dust will darken the lower part of the atmosphere, making it appear more and more as if there is a layer of dust in the air as we increase the value.
And last, with Ozone, the higher the value, the more saturated the blue sky will be. With a high altitude and Ozone value you will get an almost complete blue skybox.
Hosek/Wilkie sky texture settings
Hosek-Wilkie is supported in both Cycles and Eevee. It has three settings.
We can click and drag the orb interface to change the direction of the light.
Both Hosek-Wilkie and Preetham have a lot fewer settings than Nishita. But both use the term turbidity. Turbidity is a term describing how transparent something is. So, my understanding is that turbidity is a way to tell how many particles and how much smog there is in the air. But they implemented it differently. In Hosek-Wilkie there is a color shift from a more light blue and white to a green-brown ish color across the sky dome.
To decide what value to use, I usually think of what feeling I want to convey for the scene. A higher turbidity would give more of a sickly atmosphere telling the viewer that something is not right. Perhaps for an urban scene with high pollution.
A low turbidity may convey a more fresh and free feeling.
The ground albedo changes the tone of the ground to a more pastel while keeping the underlying color from the turbidity. It can often give a more cartoony and light feeling.
Preetham sky texture settings
For preetham we also have the vector input tool to change the direction of the light. Preetham is much like the Hosek-Wilkie sky texture with a high ground albedo value. It has a kind of pastel feeling to it. But be careful with edge values in both the vector rotation widget and the turbidity.
With a turbidity lower than 2 you can get some quite weird results. For instance, at 1.6 I get no light at all for my testings and a value of 1 seem to flip the world upside down. So keep it above 2.
Also, rotating the vector input too much will give you highly saturated colors either intense blues or yellows. This can be good to keep in mind if you intend to animate since you could cross a value that destroys the colors for a frame or so. It could be better to stick with Nishita or Hosek-Wilkie.
Personally I rarely use Preetham, but occasionally it can be useful in Eevee since it is supported there.
How to animate the sky texture?
One benefit with the sky texture over a hdri image is that we can animate the parameters. By animating the sky texture we can create a time lapse, making the sky change over time. The easiest sky type to animate is the Nishita sky texture because here we only deal with parameters and not the vector. The downside being that it is only available in Cycles.
With Nishita, the easiest way to get started is to animate the sun elevation and rotation values. Make sure that you have a 3D viewport, the shader editor and a timeline editor available in your interface and follow these steps.
If you now play the animation, it is likely that you won’t see what happens because Cycles can’t render the frames in real-time. Instead, we need to render a scene. Press Alt+F12 to render an animation from the camera.
The finished animation is stored in c:\tmp\ by default.
With Preetham or Hosek-Wilkie we can animate the sky by moving the orb.
To preview the animation, switch to Eevee and press play in the timeline editor.
How do I setup an hdri environment in Blender?
To set up an hdri as the world material in Blender, follow these steps:
In Eevee, we consider the light coming from the environment indirect, and therefore does not cast shadow. For any shadows to appear we need to bake the lighting using an irradiance volume.
You can find free hdri images to light your scene here:
My sky texture in Blender is all white.
This is a common error for beginners.
There are three types of sky texture modes on the sky texture node in Blender. The default, Nishita, is not supported in Eevee and instead produce a white sky. To solve this, switch from Nishita to Hosek/Wilkie or Preetham instead or switch your render engine to Cycles. All sky texture types are supported in Cycles.
Final thoughts
We have now covered how to set up and configure a sky texture in Blender. We looked at most settings for the sky texture types and also covered how to set up an hdri as an alternative.
Together with emission shaders and light objects, the world material covers all our ways to light. Sky textures is then one part of how we can use the world material or skybox. Just like with texture nodes, we can further expand how the world material should behave with additional nodes.
Как сделать скайбокс в блендере
This guide is about adding a sky box in Blender using Dynamic Sky on the Add-On.
Dynamic Sky is a free add-on in Blender, you just need to activate it.
Go to Edit > Preferences > Add-On > Type «Lighting: Dynamic Sky» on the search option.
After that, check mark the add-on.
Press the tab on the right of the view port and it will expand the option.
After that press the «Create» button.
Press Create on the «Dynamic Sky», then go to «World Properties»
Press the «Browse World» and select «Dynamic_1».
After you select «Dynamic_1», select «View» at the top of «Create» and go back to «Create»
That will refresh the view port so the sky box will appear.
The «Sky Color» will change the color of the sky.
«Horizon Color» will change the atmosphere of the area.
«Cloud Color» will just change the color of the clouds.
OPACITY
Lowering the opacity will not make the cloud visible.
Increasing the opacity will increase the visibility of the clouds.
DENSITY
Lowering the density will flatten the clouds.
Increasing the density will make the clouds more scatter.
Sun control will change the lighting color of the sun.
SUN VALUE
Increasing the value will make the lighting more brighter.
Lowering the value will blend the lighting from the sky you’ve colored.
SOFT & HARD
Lowering the value will soften the lighting while increasing the value will make the lighting more bright.
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Render a Skybox Environment Map
Contents
Resources
The following tutorial discusses this process, of setting up and rendering a basic skybox, using «Bender Render» («Blender Internal«), for use in game development. A basic understanding of Blender is recommended but not absolutely necessary to get the most from the content below.
Skybox set-up ^
The basic elements used to render a Skybox environment map, an upper and lower dome representing ‘sky’ and ‘ground’, and a reference point, usually located grid-centre, which forms the point of view from which rendering takes place («Camera» and «Lamp» objects visible in the Scene are not explicitly used for Skybox rendering)
Make a Skydome ^
To create a simple Skybox generator the first elements to set up are the upper and lower domes for the ‘sky’ and ‘ground’. Starting with a «New» Scene in Blender («File » New«), select the default Cube and move it to an unused layer; right-click the object then press «M» to access the «Move to Layer» pop-up, left-click one of the buttons selecting the layer to which the object will be immediately moved (it will disappear from view).
The Skybox is made using Blenders default Scene, which typically contains a ‘Cube‘, a ‘Camera‘ and a ‘Lamp‘ object. Although the lamp and camera are not explicitly used for Skybox generation, the latter item needs to be physically in the Scene (even though it’s not the point of view through which rendering takes place)
The default Cube is in the way at present but rather than delete it, it can be moved to another layer for use later on in the process. Press «M» and left-click a button to move the object
As the Skybox is actually made from a sphere one needs to be added to the Scene. Press «Shift+A» and select «Mesh » UV Sphere» or use the «Add» menu in the 3D View Header, choosing the same options. An object appears along with a set of properties (use default settings)
The default «UV Sphere» object is relatively small so needs to be resized to fit the Cube inside at a later stage in the process. SImply right-click to select and press «S» to «Scale«
Next the sphere needs to be split into two sections for the ‘upper’ and ‘lower’ elements of the Skybox. Whilst still selected press «Tab» to toggle into «Edit Mode» (or select «Edit Mode» from the «Interaction Mode» selector in the 3D View Header) then press «B» to activate and use «Box Select» to left-click drag out a drawn selection area over the upper half of the mesh, which then highlights to confirm.
Design note: making a selection that needs to include the front and back of an object may require switching to «Wireframe» mode to make the selection easier. Press «Z» to enable «Wireframe» or click the «Display Mode» button in the 3D View Header. Alternatively from the Header again, click the «Limit selection to visible» button to enable/disable as appropriate to make selections. Note also that before making a selection the mesh may need to be cleared of any previous selections by pressing «A«, «(De)select All«.
Once selected the upper section can then be detached as a completely independent object using the «Separate» function. To do this, from the «Mesh» menu option in the 3D View Header click «Vertices » Separate » Selection» (or alternatively press «P » Selection«). This detaches the vertices creating a brand new object whilst leaving the unselected elements alone.
Design note: when using the «Mesh» Header menu option, «Separate» is only available under «Vertices» whereas when using the shortcut, «P«, «Separate» is accessible as a pop-up in «Vertex«, «Edge» or «Face» select mode.
Press «B» to use «Box Select» to highlight the upper half of the mesh. This can then be detached, using «Separate«, as a completely independent object whilst leaving the lower half untouched
Once the selection is made from the «Mesh» menu click «Separate » Selected» to detach the highlighted vertices as a completely unique object.
. which now means the sphere is made from two domes, one each for the ‘sky’ and ‘ground’
The final adjustment to make is to increase the size of the upper section slightly so its larger than the lower, which it can overlap slightly. To do this press «Tab» to exit «Edit Mode» and making sure the mesh is selected press «S«, then «Ctrl«, to «Scale» the upper dome a little whilst snapped to the grid. Left-click to confirm. Once done left-click drag the «Z» axis handle of the manipulation widget (blue handle) and move the upper dome down so the first row of faces belonging to both lower and upper overlap. Release LMB to confirm.
To allow a small degree of tolerance for the grounds horizon to be inclusive of alpha masks and transparencies there should be some overlap between the upper and lower domes. Once rescaled slightly, move the upper mesh down so the first row of faces overlap between the two
Initial Materials ^
Once the upper and lower dome meshes are set up they next need to be assigned a basic Material before then being UV Unwrapped and assigned their respective images, essential to ensure the eventual Skybox is rendered correctly.
To add the Materials select the upper dome and from within «Material» Properties click the button titled «+ New» just below the empty aperture at the very top of the panel. A set of properties and options will immediately appear. In the «Diffuse» sub-section left-click the small bar tined off-white, a colour-picker will be shown. Left-click somewhere in the wheel to make a selection then press «Enter» or left-click elsewhere on-screen to confirm. In the «Material datablock ID» text input field directly under the aperture (which now displays the Material data being edited) left-click and type an identifying name, «sky» in this instance. Press «Enter» to confirm or left-click elsewhere on-screen.
Design note: objects tend not to have Materials assigned when added to the Scene by default but if one is available simply change the «Diffuse» colour and «Material datablock ID» for each to uniquely identify them. As the lower and upper were previously part of the same object any changes to pre-existing assigned Materials will duplicate. To change this select either object and to the right side of the datablock input field click the «+» button. This makes a new unique instance of the original Material, duplicating and propagating over it’s options and settings for independent editing.
Once the Material has been created change the «Diffuse» colour to make it easily identifiable and assign a unique «datablock ID» («sky» in this example)
Next in «Texture» properties, again click the button marked «+ New» to generate a set of default options. Left-click the «Unique datablock ID name» input field directly under the aperture list (which now also displays the Texture data currently being edited) and type a new name, «sky» in this instance. Press «Enter» to confirm or left-click elsewhere on screen. Change «Type:» to «Image or Movie» by selecting that option from the drop-down menu. Then from the «Image» sub-section click «+ New» to access the «New Image» dialogue, editing the «Name«, «Width» and «Height» of the image to be generated as appropriate. Click «OK» to create and automatically associate the new image with the Texture and Material data. Repeat the steps so both objects each have their own «Material«, «Texture» and «Image» data.
Design note: the result should be two independent Materials, in this instance «sky«, tinted light-blue and, and «ground«, tinted bright-green. For more information on using Materials with «Generated» images click here.
In «Texture» Properties, which should be blank, left-click an available slot in the aperture (red/white checker icon) then click the «+ New» button to generate a generic set of options
This initial phase simply generates a basic Material that makes use of default data and options, and assigns a generated image that will be used once the object is UV unwrapped
Repeat the process for the remaining dome object so it too has an independent Material, (‘green’ shown to identify ‘ground’) with generated image assignment
UV Unwrapping ^
Once the initial Materials are in place the images generated during that process can then be assigned to the upper and lower domes though «UV Unwrapping«.
Design note: although there are a number of different ways objects can be textured and UV unwrapped, for game related content the application of standard Materials and «UV» mapping is sufficient for purpose.
As much of the UV mapping process takes place in the «UV/Image Editor» it will need to be visible, but not necessarily the focus of the User Interface. So either, swap the «Outliner» view top-right for the «UV/Image Editor» by left-clicking the «Editor type. » button to the left-side of the Header, selecting the option from the list. Or from the main application Header running along the top of Blender click the «Choose Screen Layout» button, selecting «UV Editing» from the the options available.
Design note: because the UV maps being generated for these types of projects are relatively simply there is no real need to switch completely to the UV/Image Editor, so long as it can be seen and basic manipulations are possible, it can occupy a smaller area than might otherwise be used, subject to User preference.
Once the «UV/Image Editor» is visible, select the upper dome and «Tab» into «Edit Mode«. Select the entire structure of the mesh, «A«, and then from the 3D View Header select «Mesh » UV Unwrap » Unwrap«. Alternatively press «U» then select «Unwrap«. This unwraps the objects UV’s as a flat grid of points and lines, which appear in the UV/Image Editor.
Design note: when using «A» to «Select All» the key may need to be pressed twice, once to DE-select active selections then once again to RE-select everything.
To assign an image to the newly generated UV Map, from within the «UV/Image Editor» whilst the objects UV’s are visible, click the «Browse Image to be linked» button in the Header and select the named entry associated with the image previously generated per the Material that’s assigned to the mesh, in this instance «sky«.
Design note: images generally cannot be assigned to UV’s unless those UV’s are visible in the «UV/Image Editor«, even if the image is available and selectable in the «Browse Image to be linked» list (such selections will appear in the UV/Image Editors workspace but not on the mesh). To ensure selections are correctly assigned the entire mesh needs to be actively selected in «Edit Mode«.
The UV/Image Editor will display the image selected in the workspace with the UV map superimposed over the top, both of which are confined to a fixed area determined by the dimensions of the image itself (typically a ‘square’ or ‘rectangle’ shape). In the 3D View the image may not appear mapped to the mesh, if this is the case press «Alt+Z» to switch «Display Mode» to «Texture» confirming assignment. Repeat the process so both domes are UV Unwrapped and mapped with their respective generated image.
With the mesh UV Unwrapped the previously generated image can be assigned using the UV/Image Editor by selecting the entry from the «Browse Image to be linked» list («sky» in this instance)
The process of UV Unwrapping and assigning an appropriate image to an object needs to be repeated for the remain half of the full dome («ground» in this instance)
extra Material settings & Replacing Images ^
Once the upper and lower domes have been UV mapped their Materials can be further edited to add a secondary setting that changes the way light affects the scene, one that essentially makes selected items appear ‘full-bright‘. This is the «Shadeless» property and by activating, the scenes lighting no longer has influence over the way objects appear lit, which in-turn ensures the rendered Skybox contains no out-of-place shading or shadows.
To activate «Shadeless» select the object to be affected then under «Material» Properties scroll down to the «Shading» sub-section and left-click the checkbox to the left of the heading to activate. The image will immediately appear flat-lit in the 3D View, visually confirming the change. Repeat the process for the remaining dome object.
Once «Shadeless» is set, check each Materials «Image» properties to ensure the correct data is loaded in for use, for example swapping out the temporary «Generated» data for any actual bitmaps to be rendered.
Design note: using «Generated» data has some initial advantages for Materials in that their general size can be changed on-the-fly without unduly hindering other aspects of development. It can also be saved out for editing, reloaded back in once the final details are determined. To save generated image data, from the UV/Image Editor use the «Browse Image to be linked» button to select the unsaved data so it’s active in the viewport (in instances where more than one datablock is available), then from the «Image*» Header menu select «Save As Image» or «Save A Copy«, the difference being the former replaces the image currently active to the Material then references an an actual bitmap, the one just saved, versus the latter which saves a ‘copy’ of the active data whilst leaving the active, but generated, image in place.
To load a replacement, in «Texture» Properties scroll down to the «Image» sub-section and first left-click the «Source» drop-down menu and select «Single Image«, this informs on the type of image data being represented, in this instance a single image bitmap, then click the «Open file browser» icon. The interface will switch to the «File Browser«. Find and then left-click select the bitmap to be used and click the «Accept» button top-right. Blender will return to the previous screen with the image loaded into the Material and displayed on the object. Repeat the process for the remaining object. Once done the basic set-up of the background is complete and ready for use. Next the Cube object previously moved to another layer needs to be prepared.
Before loading in a replacement image some of the Materials settings need to be changed. In «Texture» Properties switch «Generated» to «Single Image«[1] then click the «File» button[2]. (the mesh may appear ‘pink’ during at this point indicating an image (bitmap) has not yet been assigned or is missing)
In the «File Browser» that opens, left-click select the bitmap that’s to be loaded in replacing the previously «Generated» image data then click the «Accept» button top-right
The «Generated» image data replaced with more appropriate ‘sky’ and ‘ground’ bitmaps for both upper and lower dome. The Scene is almost ready for rendering
EnvBox, Material & Settings ^
The second aspect of setting up a Skybox for rendering is to add, or create, an «Environment Box» (or «EnvBox«) to serve as the ‘camera’, or the point of view, through which the Scenes contents are considered and rendered. In this instance the default Cube previously moved to another layer.
Design note: the standard «Camera» object cannot be used in a general sense for environment map rendering because it only looks at the Scene from a single fixed point-of-view. Using a cube solves this because each face of the EnvBox represents a ‘perspective’ or ‘view’ of the scene, a ‘side’ (‘left’, ‘right’, ‘front’, ‘back’ etc.) of the final rendered «Environment Map«. The physical size of the cube isn’t so important as its shape, which should be cubic.
First if the cube was moved to another layer left-click the «Visible Layers» button representing that to display the object, then make sure its located at the Scenes centre. To do that right-click the object and check its «Location» data in «Object» or «View» Properties («N«), each «X:«, «Y:» and «Z:» value should be «0.00000«. If not left-click each input field in-turn and type the correct value. Press «Enter» to confirm or click elsewhere on screen.
Design note: activating «Shadeless» for the ‘EnvBox’ serves the same/similar purpose as for the domes, it ensures the final render is not unduly affected by lighting and shading (subject to requirements of the scene).
Once a Material has been assigned to the cube, from «Material» Properties activate «Shadeless» (under «Shading«) to disable the effect light/shading has over objects in the Scene and the Environment Map during the rendering process
Next in «Texture» Properties change the «Type» to «Environment Map» by selecting that option from the drop-down menu below the ‘name’ input field. A set of properties will appear under a new «Environment Map» titled sub-section. Here left-click «Static» to activate single image rendering [1] ; make sure «Mapping:» is set to «Cube» [2] ; change the «Resolution:» of the map to be rendered [3] ; and optionally alter the «Clipping:» distances [4] to make sure the entire Scene is included for consideration and rendering.
Design note: when changing the maps «Resolution:» bear in mind the value used relates to the shortest side of the map, usually the vertical axis; at «1024» the result would be an image that’s 1536 pixels wide by 1024 pixel height, i.e. six 512×512 panels (one for each side of the EnvBox cube) forming a 3W x 2H grid.
For the cube to be useful the «Type» of Material its mapped with needs to be changed to «Environment Map» by selecting the option from the drop-down list in «Texture» Properties.
The most important aspect of rendering Environment Maps is to set the object which forms the renderer’s point of view of the Scene. This is done changing the «Viewpoint Object» property[5] to use a specific item, in this instance the Cube (called «Cube»), selected from the ‘object list’
Render Environment Map ^
Before rendering the environment map an image format needs to be set in «Render» Properties because the option is not provided at save. Click the «Render» Properties button (‘camera’ icon) and scroll down to the «Output» sub-section, here click the «File Format» drop-down menu (bottom-left of the section) and select «Targa Raw«, «BMP«, «Tif» or other loss-less image format.
Design note: preference should be given to the use of ‘raw‘ or uncompressed image formats, or failing that to ones that makes use of lossless compression. Avoid jpg or other aggressively compressed formats at all costs as they often contain compression artefacts, banding, patterns etc., that can be magnified in-game, especially when projected as an environment background.
Once the format is set make sure all elements that need to be rendered are visible in the 3D View («Shift+LMB» layers where used). Then to start scroll back up to the top of «Render» Properties and click the «Render» button (displays a ‘camera’ icon). Blender will switch to the «Render View» and sequentially process the Scene (time taken will vary), rendering each projection (six) of the EnvBox as an image before finishing with a render from the camera objects point of view.
Design note: double-check an actual «Camera» object is present somewhere in the Scene else the process will fail with a «No camera found in scene» message. The image rendered as a result of the camera is not part of the environment map and can be ignored/discarded.
Ensure ALL items to be rendered are VISIBLE in the 3D View before clicking the «Render» button (the EnvBox doesn’t specifically need to be selected to render the Scene)
When processing the Scene the Environment Map attributed to the Skybox is rendered first (six panels, one for each face of the EnvBox Cube).
Design note: when saving the rendered map, the file extension may need to be manually included because *.blend is present by default (which may cause some confusion when looking for and trying to open the image).
. in the «File Browser» type the file extension being saved to, i.e. *.tga, *.bmp etc., and then click the «Save Environment Map» button top-right
Alpha Masks & Transparency ^
Design note: Materials are initially created with «Use Alpha» active by default. If alpha-masking or transparency is not found Materials are treated as standard.
Simply activating «Use Alpha» doesn’t necessarily mean transparencies are used however. For that, various properties need to be set depending on the type of transparency needed and the general behaviour required of the Material involved.
By default Materials have the «Use Alpha» setting active in «Texture» Properties even in instances where transparency is not used (the effect is ignored otherwise)
To set up transparency for Skybox rendering, first the Material itself has to be rendered transparent, then «Texture» properties have to be set so they use the alpha channel of any images loaded into the Material.
To do this, from «Material» Properties scroll down to the sub-section titled «Transparency» and left-click the checkbox to activate. Here ensure the «Z Transparency» button is active (appears blue) and that the «Alpha:» input field is set to «0.000» («Alpha: 0.000«). This forces the Materials «Diffuse» colour (and other properties that might be set) to render invisible so it has no affect or influence the outcome of processing the Scene.
Design note: the properties and options associated with «Transparency» are usually not on display and require the small downward pointing arrow to the left-side of the heading to be clicked to expand and expose them for use.
Next in «Texture» Properties scroll down to the «Influence» sub-section and from the «Diffuse:» group of options, activate «Alpha:» by left-clicking the checkbox (leave the value, «1.000», untouched). Upon activation the 3D View will update to display the areas subject to alpha transparency, confirmation the Material is now set up correctly and ready for rendering.
With the «Diffuse» properties set so they display invisible, in «Texture» Properties activate «Alpha» so the image based alpha-channel can influence the rendered transparency for the entire Material
Mid-way through rendering the ‘ground’ section is shown with a fully masked horizon as determined by the ‘transparency’ and ‘alpha’ settings of the Material (without these settings the image displays partial inclusion of the «Diffuse» colour, bright-green in this instance, where the image alpha-mask affects «Texture» but not «Material» properties)
Final environment map rendered with skyline correctly defined by the image based alpha-mask and transparency properties of the ground mesh and the Material assigned to it
Organisation & Orientation ^
The final rendered Environment Map is essentially a flattened cube with the organisation and orientation of each tile determined by Blenders Global axes. This means;
«Front» is on the positive «Y» axis («+Y», centre-top).
«Right» is to the positive «X» axis («+X», right-top).
«Up/Top» is on the positive «Z» axis («+Z», centre-bottom).
The upshot of this when using the rendered images outside Blender typically means the map will need to be edited and the tiles rearranged to fit requirements and/or cut into, and saved as, separate images where the use of a single map is not appropriate.
Design note: tiles currently cannot be reorganise from within Blender so some manual editing may be required, subject to the way ‘environment maps’ are set up in the destination technology. The prospect of having to do this highlights one of the reasons lossless image formats should be used when saving maps as compression and anti-aliasing can cause ‘bleed’, ‘smudging’ and other visual artefacts that are tricky to correct effectively, especially between strong or bright colours, an issue that becomes more apparent where tiles need to be cut up and rearranged.
The organisation and orientation of each tile within the map may differ between source (Blender) and destination technology (where the map is to be used) so some editing map be necessary, keeping in mind their respective position relative to the whole
Process Summary ^
The following is a summary of process to set up a simple Skybox in Blender to render an «Environment Map«. From the default Scene;
Sky and Ground Domes
add a UV Sphere, resize so the default Scene cubes easily fits within it.
split the sphere into two separate objects, an upper and lower dome.
resize the upper slight and overlap the lower.
assign separate Materials to each upper and lower dome.
add an Image to the Materials (either generated or bitmap).
UV unwrap the meshes using simple UV maps.
assign the respective image the each UV map and object.
set Materials as «Shadeless«.
assign a new Material to default Scene Cube.
set Material as «Shadeless«.
switch Material «Type» to «Environment Map«.
set «Environment Map» properties as «Static«, «Cube» and change «Resolution«.
set «Viewpoint Object» to «Cube» (name of default cube).
in «Render» Properties set image format to «tga» or other lossless format.
click «Render» to process the Scene.
save the results in «Texture» Properties.
Conclusion ^
The most basic form of Scene to set up and render is a sphere of two parts as described above. It works for purpose largely because of its simplicity, especially with respect to the way images are used and UV Mapped to each object. For more flexibility however, Scene can be more complex in terms of their general construction, separate objects being used for different elements. Scenes can also contain other items depending on what the background is eventually to represent, although care should be taken to avoid issues of ‘magnification’ due to in-game projection mechanisms.
Video ^
The following video shows the basic process described in the above tutorial.