How to make transparent background in blender

Transparency¶

Materials in Blender can be set to be transparent, so that light can pass through any objects using the material. Transparency is controlled using an “alpha” channel, where each pixel has an additional value, range 0-1, in addition to its RGB color values. If alpha=0, then the pixel is transparent, and the RGB values for the surface contribute nothing to the pixel’s appearance; for alpha=1, the surface is fully opaque, and the color of the surface determines the final color of the pixel.

In Blender, there are three ways in which the transparency of a material can be set: Mask, Z-Buffer and Raytrace. Each of these is explained in more detail below. The Material Preview option with a sphere object gives a good demonstration of the capabilities of these three options.

Common Options¶

The following property controls are available for all transparency options:

Alpha Sets the transparency of the material by setting all pixels in the alpha channel to the given value. Fresnel Sets the power of the Fresnel effect. The Fresnel effect controls how transparent the material is, depending on the angle between the surface normal and the viewing direction. Typically, the larger the angle, the more opaque a material becomes (this generally occurs on the outline of the object). Specular Controls the alpha/falloff for the specular color. Blend Controls the blending between transparent and non-transparent areas. Only used if Fresnel is greater than 0.

Mask¶

This option simply masks the Background. It uses the alpha channel to mix the color of each pixel on the active object plane with the color of the corresponding background pixel, according to the alpha channel of the pixel. Thus for alpha = 1, the object color is seen – the object is completely opaque; but if alpha = 0, only the background is seen – the object is transparent (but note that any other object behind the active object disappears).

This is useful for making textures of solid or semitransparent objects from photographic reference material, i.e. a mask is made with alpha opaque for pixels within the object, and transparent for pixels outside the object.

Z-Buffer¶

This uses the alpha buffer for transparent faces. The alpha value of each pixel determines the mix of the basic color of the material, and the color of the pixel is determined from the objects/background behind it. Only basic settings are available with this option; it does not calculate refractions.

Ray-Traced Transparency¶

Uses ray tracing to calculate refractions. Ray tracing allows for complex refractions, falloff, and blurring, and is used for simulating the refraction of light rays through a transparent material, like a lens.

The Raytrace option is only available in the Blender Render and Cycles render engines, but not in the Game Engine.

A ray is sent from the camera and travels through the scene until it encounters an object. If the first object hit by the ray is non-transparent, then the ray takes the color of the object.

If the object is transparent, then the ray continues its path through it to the next object, and so on, until a non-transparent object is finally encountered which gives the whole chain of rays its color. Eventually, the first transparent object inherits the colors of its background, proportional to its Alpha value (and the Alpha value of each transparent Material hit in between).

But while the ray travels through the transparent object, it can be deflected from its course according to the Index of Refraction (IOR) of the material. When you actually look through a plain sphere of glass, you will notice that the background is upside-down and distorted: this is all because of the Index of Refraction of glass.

Enable Ray Tracing

To get ray-traced transparency, you need to:

Options¶

The Transparency panel.

In addition to the common options given above, the following property controls are available:

IOR Index of Refraction. Sets how much a ray traveling through the material will be refracted, hence producing a distorted image of its background. See IOR values for Common Materials below. Filter Amount of filtering for transparent ray trace. The higher this value, the more the base color of the material will show. The material will still be transparent but it will start to take on the color of the material. Disabled (0.0) by default. Falloff How fast light is absorbed as it passes through the material. Gives ‘depth’ and ‘thickness’ to glass. Limit Materials thicker than this are not transparent. This is used to control the threshold after which the filter color starts to come into play. Depth Sets the maximum number of transparent surfaces a single ray can travel through. There is no typical value. Transparent objects outside the Depth range will be rendered pitch black if viewed through the transparent object that the Depth is set for. In other words, if you notice black areas on the surface of a transparent object, the solution is probably to increase its Depth value (this is a common issue with ray tracing transparent objects). You may also need to turn on transparent shadows on the background object. Gloss

Settings for the glossiness of the material.

Amount The clarity of the refraction. Set this to something lower than zero to get a blurry refraction. Threshold Threshold for adaptive sampling. If a sample contributes less than this amount (as a percentage), sampling is stopped. Samples Number of cone samples averaged for blurry refraction.

Examples¶

Index of Refraction¶

Influence of the IOR of an Object on the distortion of the background.

There are different values for typical materials: Air: 1.000 (no refraction), Alcohol: 1.329, Glass: 1.517, Plastic: 1.460, Water: 1.333 and Diamond: 2.417.

Fresnel¶

With ray-traced transparency.

With alpha buffered transparency.

Settings for Fresnel using ray-traced.

Settings for Fresnel using Z transparency.

The specular highlight in the F4 glass tile (which is facing midway between the light and the camera); the Fresnel effect can be seen in row C and column 6 where the faces are turned away from the camera.

The amount of Fresnel effect can be controlled by either increasing the Blend value or decreasing the Alpha value.

Depth¶

A simple scene with three glasses on a surface, and three lamps. Depth was set to 4, 8, 12, and 14, resulting in render times of 24 sec, 34 sec, 6 min, and 11 min respectively. (Download blend-file).

Increasing Depth also considerably increases render time. Each time a light ray passes through a surface, the ray-tracing algorithm is called recursively. In the example above, each side of each glass has an exterior and an interior surface. Light rays thus have to pass through four surfaces for each glass.

But not only that, at every point on a surface, some of the light can be reflected, or mirrored off the surface in various directions. This results in multiple rays needing to be calculated for each point (often referred to as a tree of rays). In each of the rendered images above there are 640Г—400=256 000 pixels. By increasing Depth, at least one tree of rays is added to each pixel.

Be kind to your computer. Carefully placing objects in a scene to avoid overlapping transparent objects is often an interesting alternative.

Hints¶

Transparent Shadows¶

No transparent shadows.

No transparent shadows, environment lighting enabled.

Transparent shadows enabled, alpha set to 0.0.

As previous, alpha set to 0.25.

Transparent shadows with ambient occlusion set to multiply, distance 1 (radius of sphere).

As previous, distance increased to 2 (diameter of sphere).

By default, the shadows of transparent objects are rendered solid black, as if the object was not transparent at all. But in reality, the more transparent an object is, the lighter its shadow will be.

In Blender, transparent shadows are set on the materials that receive the shadows from the transparent object. This is enabled and disabled with the Receive Transparent button, in the Material ‣ Shadow panel. The shadow’s brightness is dependent on the Alpha value of the shadow-casting material.

Alternatives to transparent ray-traced shadows can be found in the World tab, namely the Ambient Occlusion, Environment Lighting, and Gather panels. Alternatively, a texture can be used to control the Intensity value of the shadow-receiving material.

IOR Values for Common Materials¶

The following list provides some index of refraction values to use when ray-traced transparency is used for various liquids, solids (gems), and gases:

Gases¶

Common Liquids¶

Common Transparent Materials¶

Common Opaque Materials¶

Gemstones¶

Metals¶

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Rendering Transparent Materials and Backgrounds in Blender

November 5, 2020

There are several ways to set up materials and backgrounds as transparencies for post-processing and compositing in Blender. Below, we explore each way and walk you through the process.

Transparent BSDF

The Transparent BSDF node is at its core designed specifically for achieving transparency. Simply put, this material node allows you to control different types of transparency depending on the requirements. Like an Emission node, it can easily be inserted in a node tree within a Mix Shader and a Principled BSDF node.

Alpha Transparency

An alpha transparent material can be achieved in a similar way, with the difference being that the alpha channel of an RGBA image (BMP or PNG files) drives the transparency. It is applied using an Image Texture node and used as a masking image to the alpha input of a BSDF node.

By linking the color output to the Base Color of a Principled BSDF and the alpha output into the Shader or Factor input of a Mix Shader node, you can easily create these images using photo-manipulation software such as Photoshop or GIMP.

These kinds of materials that make use of images to visualize levels of transparency should be able to render without any issues in either of Blender’s internal engines, Eevee or Cycles, but their results may vary due to factors specific to the engine being used. The Alpha Transparency process is usually preferred in Eevee compared to Cycles.

Material Properties

Once you construct and unwrap the UV of your object in the viewport, you can begin to apply materials to it. How it renders out depends on whichever Blender rendering engine you prefer.

Materials in Cycles are built in the Material Properties tab, with the same setup as those in Eevee.

Start with a new Principled BSDF and build a node tree consisting of an Image Texture node connecting the Color output to the Base Color. The BSDF output is then sent to the surface of a Material Output node.

Select your object in the viewport if a material is not yet set up or assigned, go to the Material Properties tab and click New to make a new node setup with the Principled BSDF and Material Output nodes.

If you’re using the Image Texture node as the Base color, choose an image with a RGBA texture to apply to the object.

How to Make a Material Transparent in Blender

When your BSDF material is ready to go, and your selected image is applied on the object in the viewport, how do you make it transparent?

The next step is to add a Transparent BSDF node to the tree by selecting Add (Shift+A) and locating it in the Shader submenu. After that, you need to add a Mix Shader node, which can also be found in the Shader submenu.

Connect these nodes into the node tree by plugging in the Transparent BSDF’s output into the Mix Shader’s top shader input and dragging the Mix Shader node in between the link that connects the Principled BSDF and Material Output node so that the Mix Shader passes through the two nodes to the output. You will soon see that the transparency effect is visible on your object in the viewport.

Link the two new nodes to the node tree.

Then, link the Shader output (Mix Shader) to the Surface input (Material Output).

Transparency Control

When using either Cycles or Eevee, you can control material transparency by changing the color of Transparent BSDF’s Color vector, which changes the transparency of the image mapped to the Image Texture node. You can also change the Alpha vector of Principled BSDF, which affects the material’s overall transparency.

Once you have set up the node tree, you need to set the Blend Mode. You can find this in the Material Properties tab. At the bottom of the panel, you will find the Viewport Display options with a Settings subsection. From the Settings drop-down menu, Blend Mode will appear and you can adjust the transparency’s behavior, using the options Alpha Blend, Alpha Clip, or Alpha Hashed.

You should be able to visibly see the materials take a transparent form in the 3D Viewport.

How to Make a Background Transparent in Blender

Setting a background to be transparent is actually quite simple and an identical practice in Cycles and Eevee.

In the Render Properties tab, you will find the Film drop-down menu. Underneath the Pixel Filter subsection, there is an unchecked Transparency option. By default, this option is not activated. However, it’s the fastest way to make your scene’s background transparent in the viewport by creating an Alpha channel in your render that can then be used for compositing.

Using the UV Map Node for Transparency Map Export

Just for fun, here’s a quick tip that game designers can use. For Blender users who are more inclined to make functional game-related assets and content, or produce items used in other software like Unreal Engine or Unity, these kinds of materials can be made quickly and easily in Blender after mapping it on an object or mesh using UV mapping.

There are many ways to map objects, but one of the easiest and fun ways to do it within Blender is with the UV Map node.

In the Shader editor, click Add (Shift+A) and search for UV Map. Since the UV Map node has no input, it’s meant to be exclusively used as an output. The best place to add it is at the far left of your node tree in the vector input of your Image Texture node. Left-click to set it in place, then click the UV coordinates to be used for mapping selector and choose UV Map from the drop-down list.

Blender Makes It Easy to Set up Transparent Materials and Backgrounds

Setting up your materials and backgrounds as transparencies for post-processing and compositing in Blender is relatively easy, especially since both Cycles and Eevee share the same node-based material system (most notably, the Principled BSDF node). However, the two rendering engines do have distinct differences in overall functionality. To learn more about which engine is ultimately the best option for your project, be sure to head over to our comparison of Blender’s three built-in rendering engines: Workbench, Cycles, and Eevee.

How To Make Your Background Transparent In Your Renders?

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When the focus of the image is a single object or character, you may want to get rid of any other distractions. If selling a 3D asset on a marketplace such as TurboSquid, then you may want to remove your background entirely so that only the asset gets rendered.

To make your background transparent for your renders, go to the properties panel and then go to the render tab and scroll down until you get to the film section, open this up and click on the box labeled as transparent. If you go into rendered shading, the background will appear as a checkerboard pattern, meaning that it will not be rendered. This option is available for both the EEVEE and Cycles engines.

There are a lot of benefits to making your background transparent, and it can actually make your renders look more professional, here is why?

Reasons Why You Should Consider Making Your Background Transparent?

The first reason why you would want to remove the background for your render is to eliminate background lighting. Your environment has a strength value that when set above 0 is going to emit light across your entire scene, but because the environment itself emits light from all angles, there will be no shadows.

The second reason for removing your background is for prepping an object for publishing on a marketplace where that asset can be sold. When listing an object for sale you need to ensure that in at least one of your images that the model is by itself with no distractions.

Tip: it’s also ideal to create renders of your objects in full scenes as well to give viewers an impression of what objects will look like in that type of scene.

The third reason why you would be looking to remove your background image is when you may want to overlay it with another image that has its own background, or as a visual effect in animation or film. For example, you film a scene where a real-life person is talking to a cartoon rabbit character.

You create the animation of the character, get rid of the background, and then overlay the character into the film footage using the video sequence editor.

Do I Need To Use A Specific Render Engine For Transparency?

You do not need to use a specific render engine if you want to make your background transparent. This effect is the same for both the EEVEE render engine and the Cycles render engine and can be found in the same location.

For both render engines go to the render tab in the properties panel and locate the Film option, then click on the checkbox to make your background transparent.

Note that because this is a render effect, you will only dee the checkerboard background, which indicates transparency, in the rendered shading mode and in the render itself.

While making the background transparent is the same in both engines, keep in mind that the process of making actual objects transparent is slightly different between each engine, as this relates to changing the appearance of the material of the object rather than simply hiding it.

Make Sure To Use An Alpha Channel In Your Render Settings

Even if you have set up your scene correctly you may find that your background is still visible in the render. The main reason why this would be the case is that your render output does not have an alpha channel.

For example, a jpeg, which is a common file type that does not have an alpha channel. This means that if you render your scene as a jpeg you won’t get the transparent background.

The best thing to do here is to use a PNG file, which does have an alpha channel. If you go to the output tab in the properties panel and then open up the output section, you will be able to change your file format. Simply changing it will not fix the issue though, as you will still need to enable the alpha channel.

If you change to the PNG file format, you will see a setting for color and the options of BW, RGB, and RBGA.

BW is black and white, so the image will be greyscaled.

RGB is the default red, green, and blue channel setting for adding color to the image.

RGBA is red, green, blue and alpha for using both color and alpha channels.

By default it will be on the RGB setting, so make sure to switch it to the RGBA setting.

You can also go through the alternative options to see which formats have the RGBA setting.

Can I Make Objects Transparent Instead?

Objects can be made transparent in one of two ways. The first method is to adjust the transparency of the material using a node such as the glass node, or a transparent node. The second method is to use the holdout node, which makes the object transparent and uses the outline of that object to make that part of the scene transparent.

What’s The Difference Between Transparency And Holdout?

There is a big difference between the two, as the transparency node is a much more commonly used node for adjusting the look of the material. If you use the transparency node by itself, the object will become completely invisible and you will be able to see objects that are directly behind the transparent object.

This is true for the Cycles render engine but not for the EEVEE engine, where using the transparent node will actually turn the material’s surface black.

This is not a permanent effect, however, as you simply need to activate an additional setting. Go to the material tab in the properties panel and scroll down to where it says Settings, then change the blend mode from opaque to alpha blend, and the object should now be transparent in EEVEE.

The holdout node is different, as it uses the outline of the shape of the object to create a cutout of transparency in the scene. This means that if you use the holdout node on an object, you will see the checkerboard effect on that object, even if transparency has not been applied to the environment.

It also means that you can not see through that object and that any other models on the other side of the object cannot be viewed unless you orbit your viewport camera.

When To Use Either Node?

The transparency node works best to create an alpha channel for materials when it’s working with other nodes, for example, you can mix the transparent node with the principled shader to create a balloon material.

The holdout node is very useful if you plan to edit your image or animation after the initial render. For example, you have a scene of a living room with a TV, and you use the Holdout node on the TV screen. You can then edit the animation in the compositor and import a movie clip that you can position to play on that tv screen.

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Want to master Blender? Click here! and get our E-Book

When I first came across a situation when I needed a transparent image in Blender, I didn’t have any idea how to make that happen. But when I learned about shaders and the node editor, I found the answer.

To use an image textures alpha channel in Blender we need to set up a material that combines a shader node like Principled BSDF with a transparency BSDF node. We mix the two shaders together with a mix shader and use the alpha channel from the image texture node as the factor input.

Let’s cover the details on how we achieve this in both Eevee and Cycles as well as some possible caveats and downsides that we may encounter.

What is transparency and its prerequisites?

The words transparency and alpha are often used interchangeably. They are after all, almost the same thing.

If there is a difference between them you can say that in an image, we have red, green and blue channels. But in some image types, such as a PNG file, we may have a fourth channel that we call alpha. Alpha is then used to create transparency.

To use transparency, we therefore need an image with an alpha channel. We also need to make sure that the alpha channel isn’t empty, which can be the case with many image files. If an image has an alpha channel, you will generally know that it does.

The image format we are using also needs to support an alpha channel. A JPEG for instance does not support alpha, while PNG files does. There are other file types that also support alpha, but PNG is the file type you are most likely to come across.

There are also alternatives. For instance, we can use the built-in procedural textures in Blender to generate an alpha channel. All an alpha channel really is, is a gray scale image. A mask.

We could use any of the other channels in an image and tell Blender that we, for instance want to use the Red channel as alpha. But we are getting ahead of ourselves here.

How to set up a material for transparency in Blender

These are the steps we follow to use an image with alpha transparency in Cycles.

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If you are interested in an overview of Eevees render settings you can find my guide here that covers most sections from shadows, indirect light to film settings where we find background transparency.

Also, here is the same article, but for Cycles.

This is the final node setup. The key is to use the alpha output of the image texture as the factor, deciding what pixels in the image are transparent and what pixels are not.

An alternative way is also to connect the image alpha directly to the principled BSDF alpha and skip the transparent BSDF and mix shader all together. But the above solution is move universal and will work with other shaders as well.

If you are new to nodes you may want to check out my beginners guide on how to create materials in Blender

How to test the alpha transparency using Cycles?

To test that it works, make sure that you are in Cycles render engine and go to rendered preview mode using the button in the top right corner of the 3D viewport.

If you don’t see any transparency, double check your node setup against the image above and make sure that your image actually has an alpha channel by following the instructions below.

If at some point, your transparency becomes black, you probably have more transparent layers on top of each other than your Cycles render settings currently allows.

To fix this go to the render tab and find the light path section. Here you will find transparency bounces. By default, this is set to 8. This is how many transparent layers the ray will allow before it terminates and possibly render black.

In certain situations, for instance in trees with leaves that has alpha around them, this may not be enough, and we may need many bounces for the tree to look realistic. This is where you control this.

How to check that an image has transparency in Blender?

The easiest way to check if an image has an alpha channel is by using the node wrangler add-on. Enable it by going to Edit and preferences.

Find the add-on section and search for “wrangler”. Enable the add-on and close preferences.

In the shader editor, hold Ctrl+Shift and click your image texture node twice so that the alpha output gets connected to a viewer node that goes to the material output.

If you look in the 3D viewport and see both black and white areas it means that you have an alpha channel giving you transparency.

Black areas will represent the transparent areas and white will represent opaque.

How to use an image with transparency in Eevee

When we are using Eevee, the shader setup is the same as when we are using Cycles. But since Eevee is a rasterized render engine it handles transparency a bit different.

By default, we don’t have transparency enabled. Instead, we have to first choose the blend mode that we want to use.

The blend mode is set on a per material basis. You can find it if you go to the material tab in the properties panel and open the settings section. Here you will see a dropdown labeled Blend mode and by default it is set to opaque.

What is the differences between blend modes in Eevee?

We have three options when choosing blend mode in Eevee. These are:

In Eevee we have something called «per object sorting». This means that the object with its origin the furthest away from the camera will be drawn first. In some cases we may have geometry in front of another object, but the origin points may be reversed.

This may mess up our transparency in Eevee if we have multiple transparent layers.

Alpha hash bypasses this problem by overwriting the previously drawn object. But alpha hash uses samples and may create a noisy result with too few samples. It is also quite performance taxing.

Alpha Blend just overwrites the previous color and is probably the best option to use when we don’t have a sorting problem.

Alpha clip is the cheapest to use in terms of performance, but it works from a clip value. This means that we can’t have partially transparent pixels. We can only have full transparency, or no transparency based on a threshold.

Also take note of the shadow mode. It determines if the shadow will be drawn from the object mesh or if it should take the transparency into account and let light through the transparent pieces. The blend modes here are:

Here we have the same deal, but no alpha blend option.

None means no shadow and opaque means that we use the object’s geometry to determine the shadow.

Alpha clip will give us either a full shadow or no shadow depending on if the portion of an object lit is hitting a transparent or opaque part of the object.

Alpha hashed can give us a more nuanced shadow with light partially coming through. But at a higher performance cost and possibly noise with lower samples.

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I set up a quite simple scene to demonstrate the different modes. This is the scene in solid view. We will look from above while we use different blend modes on the material assigned to all the selected planes.

This is the material setup I used for the first example. In the alpha hash and alpha blend example I adjusted the color ramp to only include gray scale values and no black or white.

Note how I use the noise texture with a color ramp instead of an image texture alpha output. Both would work fine. All an alpha channel is, is a gray scale image anyway.

In this example we use alpha clip for both shadow and blend mode. I have a low sample count of 16 that contribute to the poor shadow quality.

This is the alpha blend example. We have no noise, and we can use values in between full black or full white to create a partial see-through environment.

In this last example I increased the samples to 128. You can see that it is still quite noisy and would require more samples to clear up. At 512, I started to get something comparable to alpha blend in this case.

Something I found when testing the shadow was that alpha clip often is enough to create fairly accurate shadows if we use soft shadows.

More about soft shadows in my guide to Eevee settings. It is the same link as above.

When dealing with transparency we often have geometry without depth to them. Such as simple planes. In this case we may see the backside of a face. If you need to turn off the backside view of faces you can use backface culling found at the top of the material settings.

What is the difference between transparency BSDF and holdout?

You may have heard or seen that there is a transparent BSDF as well as a holdout shader node. Both have to do with transparency.

The transparency BSDF will render as transparency based on the blend method for Eevee or just as transparency in Cycles, revealing whatever is hidden behind partially or fully.

The holdout node will cut a hole in the canvas, leaving a transparent mask in the final render.

Final thoughts

There is a lot more to transparency in Blender. In this article we focused on how to use alpha in a texture. In essence, alpha is just a black and white mask. But it is so fundamental to a lot of computer graphics.

We can have a transparent background, we can use the compositor to work with green screens, and we can mask however we want with procedural texture nodes in our materials just to name a few places where we use transparency and masks.

How to make transparent material in cycles?

Is it possible to make a transparent Material in cycles render? How is it accomplished?

4 Answers 4

An image texture with alpha(transparency) data can be used to make transparent materials. Do note that in order for alpha textures to work the image file format requires an alpha channel or be a grayscale mask.

Though my original answer is still applicable and functions. There have been many updates and enhancements since then. One of them being the inclusion of a PBR shaders, Principled BSDF hese specifically. Which, as of v2.8, now also has an Alpha input. Simplifying transparency in many ways.

The following examples utilize a 2px by 2px checker pattern with full black and full alpha transparency.

Blender 2.8

Node setup using ‘Alpha Channel’ with Principled shader:

Blender 2.7

In this example; the Transparent Shader is set to white #FFFFFF which produces full transparency. This is then connected to the top input of 2 Mix Shaders.

Alpha from Image Texture is connected to the factor input of first Mix Shader. This takes the alpha data from the image and essentially applies it as a mask.

The color data from the image is not used in this case. Though, when applicable, can be connected to the color input of a shader. Such as mesh based hair and eyelashes for example.

The first Mix Shader connects to the bottom of the second. This allows control of the overall opacity.

Alpha node setup/example:

A black and white and/or grayscale image can be substituted.
Black being fully transparent and white being fully opaque. Use color output instead of alpha.

Grayscale node setup/example:>Note:

Some raster formats that support alpha are:

I would suggest use of OpenEXR when working with raster images containing an alpha channel. For Photoshop users I recommend the exr-io plugin.

For those using vector images. To my knowledge SVG is the prime candidate.

Note 2:
The shader used for color can be changed as desired and/or needed. This will also work with volumetric shaders as well. However do understand that volumetrics work a little differently than surface shaders. Any further detail on that would be getting a little too far off topic.

Special thanks to Mr Zak and troy_S for their insights in the comments.