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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Clipping polygon faces through a polyhedron of vision

A flight simulator combines flight data and polygon face terrain data to provide a CRT display at each window of the simulated aircraft. The data base specifies the relative position of each vertex of each polygon face therein. Only those terrain faces currently appearing within the pyramid of vision defined by the pilots eye and the edges of the pilots window need be displayed at any given time. As the orientation of the pyramid of vision changes in response to flight data, the displayed faces are correspondingly displaced, eventually moving out of the pyramid of vision. Faces which are currently not visible (outside the pyramid of vision) are clipped from the data flow. In addition, faces which are only partially outside of pyramid of vision are reconstructed to eliminate the outside portion. Window coordinates are generated defining the distance between each vertex and each of the boundary planes forming the pyramid of vision. The sign bit of each window coordinate indicates whether the vertex is on the pyramid of vision side of the associated boundary panel (positive), or on the other side thereof (negative). The set of sign bits accompanying each vertex constitute the outcode of that vertex. The outcodes (O.C.) are systematically processed and examined to determine which faces are completely inside the pyramid of vision (Case A--all signs positive), which faces are completely outside (Case C--All signs negative) and which faces must be reconstructed (Case B--both positive and negative signs).

Rohner, Michel A.↗
NASA NTRS2024

Preventing Camera Clipping Through Varied Terrain and Other Planetary Objects

Within the scope of computer visualization systems and technologies, camera objects allow users to navigate three-dimensional (3D) scenes much like a person would navigate the real world. As such, when one seeks to model a scene or environment based on real-world laws, the camera must often follow these same conventions. Accomplishing this in the world of computer renderings presents unique challenges for defining space, spatial relations, depth, distance, and height. Therefore, movement for a camera must be specifically designated and processed by the program in order to achieve accurate movement representations. Although this thought process involves each aspect of camera movement, one specific aspect of camera movement is the primary focus of this report: ensuring that the camera does not clip through an object and appear subsurface. This is important to mimic real-world movements because people in the real world would not go beneath the solid-surface terrain unless they intended to do so. By working with numerical definitions, equations, and variables, a computer can relate an object to its existence in space. Thus, such challenges in camera movements with computationally rendered 3D spaces can be mitigated.

Kristie O'Brien↗
DOE OSTI2021

A Valentine’s tribute to Lab love: Watch clips from 1943 wedding of two staff

She was a secretary for Director J. Robert Oppenheimer. He was a physicist who helped create the world’s first atomic bombs. And for 65 years they were Mr. and Mrs. Bradner. Hugh Bradner was the first person that Marjorie Hall met upon arrival to join the Lab’s clandestine war-time efforts. He happened to be in Dorothy McKibbin’s Santa Fe office when Marjorie walked in. It was love at first sight, Marjorie recalled years later in an interview. The Bradners were married in September 1943 at McKibbin’s home. It was one of many weddings there during the Manhattan Project era. Los Alamos was fenced and guarded during this time, as staff raced to secretly develop nuclear weapons to help end World War II. Most were young – the average age was late 20s – and many, like the Bradners, met their lifelong partners then. The Bradners left Los Alamos after the war ended in 1945. Hugh is credited with inventing the neoprene wetsuit in 1951. The couple had one daughter. Marjorie, 89, and Hugh, 92, died just a few weeks apart in 2008 in California. Many of their home movies from their time in Los Alamos are preserved at the Lab. They are part of the collections in the National Security Research Center, which is the Lab’s classified library and also houses unclassified artifacts.

99 GENERAL AND MISCELLANEOUS↗