Gamefox642

1. Blender Learning Path
2. Blender Npr Render

I've used my Militarized Police model to make some cover art for a friend's new song of the same name. Blender is an open source software for 3D modeling, rendering, animation, post-production, interactive creation and playback. Freestyle NPR rendering has a new textured strokes feature, along.

No matter what your preferred style may be, not all designers are after true-to-life, photo-realistic scenes in their renderings. Non-photo-realistic (NPR) art is also in demand for 3D artists, and sometimes they want a more expressive, comic-like final render; perhaps like an animated film for kids. Blender’s solution comes in the form of Freestyle. Let’s take a closer look at what it can do, as well as a simpler option for achieving similar effects.

Contents

• Using Blender Freestyle
• Using ProRender’s ToonTrace as an Alternative to Freestyle

Using Blender Freestyle

Blender’s Freestyle is an edge/line-based function that uses mesh data and depth information to draw lines on user-selected edges. An endless amount of line styles can be produced to create all sorts of hand-drawn, hand-painted, or drafted looks.

Once enabled in your rendering settings, Freestyle provides its own set of Global Settings, as well as Line Set and Line Style settings in the View Layer tab. Freestyle will also activate its own panel to allow for further adjustment of its internal viewing and rendering settings.

Line Set Settings

The Line Set tab is the main setup for your Freestyle line presentation — where your lines will appear and on what edges. You have the option of choosing to render out with any of these Selection Modes, each of them selecting a different set of edges in your scene.

• Visibility
• Edge Types
• Face Marks
• Collection
• Image Border

Underneath these selection modes, you can change the visibility type of the line. You can choose more than one Line Set for your composition, and you can then apply an edge type to each mode you’ve selected. Edge types are where the majority of the Line Set settings are made. They allow you to have more control over the selected edges based on parameters set by each type. These types are as follows.

• Silhouette
• Border
• Contour
• Suggestive Contour
• Ridges & Valleys
• Crease
• External Contour
• Edge Mark
• Material Boundary

Each option has both a checkbox and an “X” on either side of the edge type option. The checkbox, when ticked, tells Blender to render this edge type, but if many types are selected, the “X” box can be ticked to counter an edge type if two types intersect or overlap in the camera view.

Beneath these is the Face Marks section, which gives you the choice of marking or unmarking a particular polygon face or set of polygon faces to be rendered in Freestyle. The options to make these selections inclusive or exclusive are also available.

Finally, the Collection section is found beneath Face Marks. This section enables you to select groups of layers, or collections, that will be rendered with your designated line set. To use it, select it in the Line Set options and the interface will expand. Select the collection that you want to include or exclude.

Line Style

The Line Style settings define the appearance of your Line Set setup using the following properties.

• Strokes
• Color
• Alpha
• Thickness
• Geometry
• Texture

Each property has its own independent settings on its own separate tab.

These allow you to create many different styles and renders (technical layout, rough sketches, cartoon style, calligraphic). Line styles can be augmented and changed to your heart’s content, giving you access to a great range of possibilities and effects.

With all of this creative control, things can seem a little daunting at first, so take time and tinker with the parameters to get a feeling for what each option can do for your render.

Rendering with Freestyle in Cycles

Once your render is complete, the only real way to view the resulting image is to combine it with other passes to create the full effect in the compositor. In many cases when using Freestyle, you need to combine it with tools like toon shaders and compositing nodes, or work with multiple scenes and view layers.

Cycles makes this very easy as it lets Freestyle have its own render pass. When rendering locally, it’s important to render the Freestyle lines on a separate layer with an alpha background. The only way to do that is with the compositor.

1. In the compositor, add a new Render Layer node.
2. Select the new Render Layer node and find the Render Layer tab in the Properties panel.
3. In the Filter section, uncheck all except for Freestyle.
4. In the Render tab, find the film section and check “transparent,” and confirm that Freestyle is enabled.

Rendering with Freestyle in Eevee

Eevee, on the other hand, has only recently provided this capability. Since the 2.80 Beta version of Blender, Eevee has been an internal rendering engine available for the software but has not had the ability to filter independent passes for Freestyle. However, as of this article’s publishing, Blender 2.83 and more recently 2.90 have corrected this issue. Eevee now allows for Freestyle to have its own render pass, so the compositor setup mentioned above will work as well.

Pros & Cons of Freestyle

If you’re looking to add a more cartoony, comic-like, or illustrated aesthetic to your work, or if you’re seeking to achieve a technical look to your architectural visualization blueprint, Freestyle may be what you need to achieve the look you’re going for.

Though seemingly intimidating, the significant amount of user control over line weight, shape, color, and location is a strong positive for Freestyle.

One issue, perhaps, is that it takes some time to augment and shape the type of lines you want, with as much creative control as it affords, you can spend hours tinkering with settings to get everything exactly to your desired result, which some may find frustrating.

Note: A major conflict can happen if you use Radeon ProRender as your primary rendering engine. Freestyle’s functions are currently unavailable to ProRender users, but there is an alternative that may pique your interest.

Using ProRender’s ToonTrace as an Alternative to Freestyle

ProRender’s ToonTrace is a free-to-use toon outline function that is available for all Render Pool members. Like Freestyle, ToonTrace can create lines on the edges of your pre-existing models without you having to do a thing. Though not available inside Blender itself when using the ProRender engine, this function is offered to anyone who utilizes Render Pool’s rendering services.

While you may not have as much control as you would with Freestyle, ToonTrace simplifies the outlining process. With RenderPool’s UI, you can change the line size and thickness, and choose either Material ID or Object ID render passes for render exports.

Pros & Cons of ToonTrace

The simplicity of ToonTrace is its greatest advantage. Everything is already built in and ready to use in Render Pool. Once your .rpr file is uploaded, simply activate ToonTrace in your render export settings and set your line width and AOV selection in the submenus provided.

If you’re looking for options such as stroke, color, or geometry, you won’t find them in ToonTrace. However, if you’re looking for an Architectural Visualization (Archviz) technical look, this may not be much of an issue for you.

The ability to view the result prior to rendering is also unavailable in ToonTrace. In order to change any details regarding the lines, you will have to tweak the settings and render out the scene again.

Render Pool Makes NPR Art Easy with Freestyle or ToonTrace

Whether you prefer the control and customizability of Freestyle or the speed and simplicity of ToonTrace, with Render Pool now allowing both .rpr and .blend files for upload, native Blender users have more rendering options available to them than ever before.

Happy Rendering!

Non-photorealistic rendering (NPR) is an area of computer graphics that focuses on enabling a wide variety of expressive styles for digital art, in contrast to traditional computer graphics, which focuses on photorealism. NPR is inspired by other artistic modes such as painting, drawing, technical illustration, and animated cartoons. NPR has appeared in movies and video games in the form of cel-shaded animation (also known as 'toon' shading) as well as in scientific visualization, architectural illustration and experimental animation.

History and criticism of the term[edit]

The term non-photorealistic rendering is believed to have been coined by the SIGGRAPH 1990 papers committee, who held a session entitled 'Non Photo Realistic Rendering'.^[1][2]

The term has received some criticism:

• The term 'photorealism' has different meanings for graphics researchers (see 'photorealistic rendering') and artists. For artists—who are the target consumers of NPR techniques—it refers to a school of painting that focuses on reproducing the effect of a camera lens, with all the distortion and hyper-reflections^{[definition needed]} that it creates. For graphics researchers, however, it refers to an image that is visually indistinguishable from reality. In fact, graphics researchers lump the kinds of visual distortions that are used by photorealist painters into 'non-photorealism'.
• Describing something by what it is not is problematic. Equivalent (made-up) comparisons might be 'non-elephant biology' or 'non-geometric mathematics'. NPR researchers have stated that they expect the term will disappear eventually and be replaced by the now more general term 'computer graphics', with 'photorealistic graphics' being the term used to describe 'traditional' computer graphics.^{[citation needed]}
• Many techniques that are used to create 'non-photorealistic' images are not rendering techniques. They are modelling techniques, or post-processing techniques. While the latter are coming to be known as 'image-based rendering', sketch-based modelling techniques, cannot technically be included under this heading, which is very inconvenient for conference organisers.

The first conference on Non-Photorealistic Animation and Rendering^[when?] included a discussion of possible alternative names. Among those suggested were 'expressive graphics', 'artistic rendering', 'non-realistic graphics', 'art-based rendering', and 'psychographics'. All of these terms have been used in various research papers on the topic, but the 'non-photorealistic' term seems to have nonetheless taken hold.

The first technical meeting dedicated to NPR was the ACM-sponsored Symposium on Non-Photorealistic Rendering and Animation (NPAR) in 2000. NPAR is traditionally co-located with the Annecy Animated Film Festival,^[3] running on even numbered years. From 2007 onward, NPAR began to also run on odd-numbered years, co-located with ACM SIGGRAPH.^[4]

3D[edit]

Three-dimensional NPR is the style that is most commonly seen in video games and movies. The output from this technique is almost always a 3D model that has been modified from the original input model to portray a new artistic style. In many cases, the geometry of the model is identical to the original geometry, and only the material applied to the surface is modified. With increased availability of programmable GPU's, shaders have allowed NPR effects to be applied to the rasterised image that is to be displayed to the screen.^[5] The majority of NPR techniques applied to 3D geometry are intended to make the scene appear two-dimensional.

NPR techniques for 3D images include cel shading and Gooch shading.

For enhanced legibility, the most useful technical illustrations for technical communication are not necessarily photorealistic. Non-photorealistic renderings, such as exploded view diagrams, greatly assist in showing placement of parts in a complex system.

2D[edit]

The input to a two dimensional NPR system is typically an image or video. The output is a typically an artistic rendering of that input imagery (for example in a watercolor, painterly or sketched style) although some 2D NPR serves non-artistic purposes e.g. data visualization.

Blender Learning Path

The artistic rendering of images and video (often referred to as Image Stylization^[6]) traditionally focused upon heuristic algorithms that seek to simulate the placement of brush strokes on a digital canvas.^[7]

Arguably, the earliest example of 2D NPR is Paul Haeberli's 'Paint by Numbers' at SIGGRAPH 1990. This (and similar interactive techniques) provide the user with a canvas that they can 'paint' on using the cursor — as the user paints, a stylized version of the image is revealed on the canvas. This is especially useful for people who want to simulate different sizes of brush strokes according to different areas of the image.

Subsequently, basic image processing operations using gradient operators^[8] or statistical moments^[9] were used to automate this process and minimize user interaction in the late nineties (although artistic control remains with the user via setting parameters of the algorithms). This automation enabled practical application of 2D NPR to video, for the first time in the living paintings of the movie What Dreams May Come (1998).

More sophisticated image abstractions techniques were developed in the early 2000s harnessing Computer Vision operators e.g. image salience,^[10] or segmentation^[11] operators to drive stroke placement. Around this time, machine learning began to influence image stylization algorithms notably image analogy^[12] that could learn to mimic the style of an existing artwork.

The advent of deep learning has re-kindled activity in image stylization, notably with Neural Style Transfer (NST) algorithms that can mimic a wide gamut of artistic styles from single visual examples. These algorithms underpin mobile apps capable of the same e.g. Prisma

In addition to the above stylization methods, a related class of techniques in 2D NPR address the simulation of artistic media. These methods include simulating the diffusion of ink through different kinds of paper, and also of pigments through water for simulation of watercolor.

Artistic rendering[edit]

Artistic rendering is the application of visual art styles to rendering. For photorealistic rendering styles, the emphasis is on accurate reproduction of light-and-shadow and the surface properties of the depicted objects, composition, or other more generic qualities. When the emphasis is on unique interpretive rendering styles, visual information is interpreted by the artist and displayed accordingly using the chosen art medium and level of abstraction in abstract art. In computer graphics, interpretive rendering styles are known as non-photorealistic rendering styles, but may be used to simplify technical illustrations. Rendering styles that combine photorealism with non-photorealism are known as hyperrealistic rendering styles.

Notable films and games[edit]

This section lists some seminal uses of NPR techniques in films, games and software. See cel-shaded animation for a list of uses of toon-shading in games and movies.

References[edit]

1. ^Chairman-Baskett, Forest (1990-09-01). 'Proceedings of the 17th annual conference on Computer graphics and interactive techniques'. SIGGRAPH. ACM. ISBN978-0897913447.
2. ^Simon, Schofield (March 1994). Non-photorealistic rendering: a critical examination and proposed system. eprints.mdx.ac.uk (phd). Middlesex University. Retrieved 2018-07-03.
3. ^CITIA, ©. 'Site officiel du Festival et du Marché international du film d'animation d'Annecy'. www.annecy.org. Retrieved 20 April 2018.CS1 maint: numeric names: authors list (link)
4. ^[1]
5. ^Drew Card; Jason L. Mitchell. 'Non-Photorealistic Rendering with Pixel and Vertex Shaders'(PDF). Archived from the original(PDF) on 2011-06-15. Retrieved 2010-03-08., extracted from Wolfgang F. Engel (1996). Direct3D SHADERX: Vertex & Pixel Shader Tips and Techniques. 87Wordware Game Developer's Library. Wordware Publishing. ISBN978-1556220418.
6. ^Image and Video-Based Artistic Stylisation. Computational Imaging and Vision. Springer. 2013. ISBN9781447145189.
7. ^Kyprianidis, Jan Eric; Collomosse, John; Wang, Tinghuai; Isenberg, Tobias (2013). 'State of the 'Art': A Taxonomy of Artistic Stylization Techniques for Images and Video'. IEEE Transactions on Visualization and Computer Graphics. 19 (5): 866–885. doi:10.1109/TVCG.2012.160. PMID22802120. S2CID2656810.
8. ^Litwinowicz, Peter (1997). 'Processing images and video for an impressionist effect'. Proceedings of the 24th annual conference on Computer graphics and interactive techniques - SIGGRAPH '97. pp. 407–414. doi:10.1145/258734.258893. ISBN0897918967. S2CID13139308.
9. ^Shiraishi, Michio; Yamaguchi, Yasushi (2000). 'An algorithm for automatic painterly rendering based on local source image approximation'. Proceedings of the first international symposium on Non-photorealistic animation and rendering - NPAR '00. pp. 53–58. doi:10.1145/340916.340923. ISBN1581132778. S2CID16915734.
10. ^'Painterly Rendering using Image Salience'. 2002: 122–128. CiteSeerX10.1.1.7.5383.Cite journal requires |journal= (help)
11. ^https://www.cs.utah.edu/~shirley/papers/painting.pdf
12. ^https://mrl.nyu.edu/publications/image-analogies/analogies-72dpi.pdf

Further reading[edit]

Some key papers in the development of NPR are:

• 'Paint by Numbers: Abstract Image Representations', by Paul Haeberli, SIGGRAPH 90
• 'Comprehensible rendering of 3-D shapes', by Saito and Takahashi, SIGGRAPH 90
• 'Wet and Sticky: A Novel Model for Computer-Based Painting', by Tunde Cockshott, PhD Thesis, Glasgow University, 1991
• 'Computer-Generated Pen-and-Ink Illustration', by Winkenbach and Salesin, SIGGRAPH 94
• 'Interactive Pen-and-Ink Illustration', by Salisbury, Anderson, Barzel, Salesin, SIGGRAPH 94
• 'Painterly Rendering for Animation', by Barb Meier, SIGGRAPH 96
• 'A Non-Photorealistic Lighting Model For Automatic Technical Illustration', by Amy Gooch, Bruce Gooch, Peter Shirley, Elaine Cohen, SIGGRAPH 98

External links[edit]

Blender Npr Render