Here’s a list of terms used in the production of 3D architectural imagery.
Bump Mapping – A method of simulating shallow depth surfaces by creating image-based (rather than model-based) highlights and shadows. Bump mapped effects are useful for simulating surface detail at mid-ground and background distances. The illusion breaks down completely at close distances, revealing that the object is in truth flat. Bump mapping has been partially replaced by Displacement Mapping which is more realistic because the surfaces are fully modeled in 3D. Bump mapping, however is still a useful technique because it requires far less computational power than displacement mapping.
Camera Matching – The act of creating a synthetic camera within a 3D program that matches a real-world camera, usually with the aim of compositing the resulting 3D image within a real-world photograph. Matching replicates any and all variables present on the real-world camera including:
- Focal Length
- Shutter Speed
- ISO settings
CMYK – A color model used in printing devices, standing for the four inks used: Cyan Magenta Yellow and Key Black. Inkjet printers and four-color off set printers use CMYK.
Color Management – A method and set of principles used to control the conversion of color between devices. Digital equipment such as TVs, computer monitors, and projectors process color according to the RGB color model. Print devices such as inkjet printers and offset printers process color using the CMYK model. Color management attempts to obtain a good match when translating between devices.
Color Model – Refers to one of several methods for representing colors. As it pertains to 3D digital images, the main color models are RGB and CMYK.
Compositing – The assembly of separate images into one image, accomplished with image editing software such as Adobe Photoshop or Adobe After Effects. The common principle in all compositing is the separation of images into distinct layers. Each image layer can then be manipulated without effecting other layers, thereby allowing targeted control over the final assembled image.
Digital Printing – A printing process in which the content is transferred directly to paper using digital data, rather than a mechanical process (see offset printing). Because set-up is minimal and largely automated, digital printing is economical for low production runs and/or where the turn-around time is tight. Though the quality of digital prints are generally quite good, they are not as good as offset printing. Examples of digital printing devices are inkjet and laser printers.
Direct Illumination Rendering – A method of 3D rendering that simulates lighting by calculating only the light which is emitted from active sources – for example, the sun, a light bulb, or a candle. In the real world, light is immensely complex: light leaves an emitting source and then bounces, being reflected and/or absorbed until its energy is completely dissipated. This bounced light is referred to as indirect illumination, and is responsible for creating the richly varied appearance of light and shadow in the real world. Global Illumination rendering calculates the effect of bounced light; in direct illumination rendering, this bounced light is faked by specifying a uniform “ambient” light level. Because this lighting level is uniform and flat, it looks noticeably fake compared to a real image. Direct illumination is used in 3D rendering because it is far less computationally intensive than global illumination, and was the only reasonable method to create 3D architectural imagery until about 2005. Up to this time, reasonably priced prosumer computers were simply not powerful enough to handle global illumination. Since that time, computational power and software programs have evolved to make global illumination the preferred method of creating photo-realistic 3D images.
Displacement Mapping – This is a method of creating shallow depth 3D objects from image data. A seminal example is the creation of a brick wall. A 3D modeler would create a completely flat plane and apply a displacement map. In this example, the map would be a high-contrast, gray-scale photograph of a brick wall. The 3D software uses the degree of white, black or gray in the image to add or subtract depth to the flat plane, thereby creating a detailed brick wall. Displacement Mapping is great for creating a wide array of architectural surfaces, for example brick, stone, wood and the gentle distortions of fabric upholstery. Displacement mapping must be used judiciously because it is computationally intensive and also prone to erroneous distortions if the underlying image data is not prepared properly. Displacement Mapping is a preferable alternative to the older Bump Mapping method of simulating shallow depths.
Entitlement – Refers to the process or set of procedures whereby an agency, usually of the government, grants permits approving the construction of a real estate project. Depending upon the jurisdiction, entitlement can be an extremely complex, costly and lengthy process requirement the coordination of professionals across many disciplines.
Entourage – Refers to anything added to the 3D scene to create a naturalistic sense of place and setting. The exact scope of entourage can be variable. For exterior renderings it generally means the sky, and all the other secondary objects, like people, street furniture (e.g., benches, light poles, kiosks, etc.) and plantings not specified by the designers. For interior renderings entourage mostly means furniture.
Fly-Through – A type of animation where the camera path and pace emulates that of a viewer flying through a space.
FLV – A file format used for video on the web. FLV files use various compression and streaming methods to keep file transfer times reasonable for viewing video online. Stands for FLash Video.
Geometry – A term used to refer to any 3D object. It is synonymous with Mesh
Global Illumination Rendering – A method of 3D rendering that takes into account both direct illumination – the light from emitted sources like the sun or a light bulb – and indirect illumination – the light that is bounced off non-emitting objects like a wall or floor. Global illumination rendering is capable of creating images that are highly photo-realistic, and is the preferred method for rendering 3D architectural images. Global illumination requires a great deal of computational power; until recently, professional-grade PCs were simply not powerful enough to make global illumination renderings a practical option. Starting about 2005, computer hardware and software grew robust enough to make this method practical in a production environment. The main global illumination rendering software packages are VRay, Brazil, MentalRay and Maxwell. For further information, see Wikipedia’s discussion of global illumination.
JPG – An image file format which uses compression technologies to reduce file size. JPG files, also known as JPEG, are an ideal image format for displaying images on a website.
Material – A term used to describe the visual characteristics applied to a 3D model. A material is a top-level container which specifies a large array of visual properties that are manipulated to simulate the appearance of real-world objects. Materials contain sub-level properties which the user defines:
Materials are edited and then saved to a material library where they may be reused, copied, and altered to be quickly applied to any 3D model.
Mesh – A term used to refer to any 3D object. The term is presumably derived from the fact that when viewed in wire-frame mode, objects in a 3D program look as though they are covered with mesh fabric. Mesh is synonymous with Geometry.
MPEG – A video file format that is used widely on the web because it employs compressions technologies to reduce file sizes, thereby making it practical to download or stream movies on the internet. Stands for Moving Pictures Experts Group.
Multi-Pass Rendering – A method of rendering whereby parts of a scene are rendered in isolation of the rest of the scene. The advantage of this method is that the resulting images can be edited in isolation of the rest of the scene, allowing discrete, targeted control over the constituent image parts. Multi-pass rendering relies on post-production software such as Adobe Photoshop and Adobe After Effects to composite the render-pass images into a finished image.
Offset Printing – A printing process where a metal plate transfers (offsets) ink to a rubber blanket, which then transfers it to paper. Offset printing is only economical when printing large quantities – the set up charges to prepare the plates and run the presses (which can cost millions of dollars) are high. Offset printing generally yields excellent print quality.
Optical Effects – These are artifacts left on an image as a result of the physics of light interacting with camera lenses. With the exception of distortion, these effects do not occur natively within 3D software, and must be simulated using a set of tools either within the 3D program or as a separate process in post production.
- Distortion – This is usually noticed as the elongation of objects at the edges of the image plane, and varies with the lens and focal distance settings.
- Focal Blur – This is when objects become blurry as a result of being outside of the lens focal area.
- Glow – This is caused by the scattering of light along the planes of the lens.
- Lens Flare – This occurs when a camera is pointed toward at a strong light source and takes the form of a series of prismatic bursts of color.
- Motion Blur – This occurs as a result of a shutter speed which is slower than the speed of the images being recorded.
Pan – A type of animation where the camera remains at a fixed point and rotates horizontally (i.e. side to side) around a vertical axis. Contrast with tilt.
Pixel – The smallest discrete unit of a digital image. Each pixel represents one color value; digital mages are made up of pixels assembled in a grid. Image size and resolution are measured by the number of pixels in the horizontal and vertical directions; the greater the number of pixels in an image, the higher its resolution. For further information, see the discussion of pixel on Wikipedia.
Post Production – Any process performed after the imagery is rendered by the 3D software. The raw imagery produced by 3D software often requires further manipulation. These edits often include:
- Color Balance
- Optical Effects – 3D rendering software is often not natively capable of producing many real-world phenomena such as lens flares, light-glow, focal blur and motion blur. Even if the 3D software is capable of producing such effects, the quality may be inferior to post-production methods or the processing times unrealistic for a production timeline.
Rendering – The software-driven process of translating 3D scene information into a 2D image.
RGB – A color model used on digital display devices such as TVs, computer monitors and projectors. Stands for Red Green and Blue.
Resolution – A term used to describe the amount of detail an image contains. Image resolution is related to image size, measured in horizontal and vertical pixel dimensions; the greater the resolution, the sharper the image quality. As it pertains to 3D architectural imagery, resolution can be divided into three categories:
- Low: characterized by sizes up to about 600 pixels in either the vertical or horizontal dimension. Low resolution images are suitable on websites and as email attachments because file sizes are small.
- Medium: typically defined by image dimensions greater than 600 pixels but less than 2,000. When formatted properly, medium resolution images are suitable on websites, and for printing small sized images (up to about the size of a postcard).
- High typically defined by images greater than 2,000 pixels in either the vertical or horizontal dimension. High resolution images are used for printing images; because their file sizes can become quite large, high resolution images are generally not advisable for use on websites.
Further information can be found on Wikipedia’s definitions of image resolution.
Streaming Media – A category of web-based file formats for animations and videos designed to minimze the amount of time a user must wait for the content to start playing. Animation and video files can be very large, and so wait-times on the internet are a major concern; streaming media sends partial segments of the file, rather than all of it, allowing a user to start watching sooner than they otherwise would. By the time they are ready for the next part, it will have downloaded as they were watching the first part, and so on, until the conclusion. For more information see Wikipedia’s article on streaming media.
Texture Map – A subset component of a material, a texture map (also known simply as a texture) is an image that is projected onto a 3D object to replicate a real-world counterpart. Textures come in two varieties: photographic and procedural. Photographic use photos of actual objects; procedural are generated by software code. For example, to create a brick wall material, a 3D modeler would simply apply a texture which uses a photograph of a brick wall.
Texturing – A term used to describe the overall process of defining the visual properties applied to 3D models. This includes creating materials, defining textures maps, applying the materials to objects, and modifying the 3D objects.
TIFF – Stands for Tagged Image File Format. TIFF files are the preferred file format to use when printing images.
Tilt – A type of animation where the camera remains at a fixed point and rotates vertically (i.e. up and down) around a horizontal axis. Contrast with pan.
Viewshed – A field of view from a fixed vantage point. The term is usually associated with urban planning whereby views of historically or environmentally important areas are designated as worthy of special consideration and protection.
Walk-Through – A type of animation where the camera path and pace emulates that of a person walking through a space. Because 3D cameras are not subject to the same constraints as real-world cameras, 3D animations can combine walk-through and fly-through techniques.
Zoom – A type of animation where the camera remains at a fixed point and the focal length of the lens is altered to move closer or farther from the subject.