Search NASA⌕ Search

SEARCH · Search NASA

Results for “Terrain”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Modeling and Visualizing Flow of Chemical Agents Across Complex Terrain

Release of chemical agents across complex terrain presents a real threat to homeland security. Modeling and visualization tools are being developed that capture flow fluid terrain interaction as well as point dispersal downstream flow paths. These analytic tools when coupled with UAV atmospheric observations provide predictive capabilities to allow for rapid emergency response as well as developing a comprehensive preemptive counter-threat evacuation plan. The visualization tools involve high-end computing and massive parallel processing combined with texture mapping. We demonstrate our approach across a mountainous portion of North California under two contrasting meteorological conditions. Animations depicting flow over this geographical location provide immediate assistance in decision support and crisis management.

Kao, David↗
NASA NTRS2006

Automated, on-board terrain analysis for precision landings

Advances in space robotics technology hinge to a large extent upon the development and deployment of sophisticated new vision-based methods for automated in-space mission operations and scientific survey. To this end, we have developed a new concept for automated terrain analysis that is based upon a generic image enhancement platform|multi-scale retinex (MSR) and visual servo (VS) processing. This pre-conditioning with the MSR and the vs produces a "canonical" visual representation that is largely independent of lighting variations, and exposure errors. Enhanced imagery is then processed with a biologically inspired two-channel edge detection process, followed by a smoothness based criteria for image segmentation. Landing sites can be automatically determined by examining the results of the smoothness-based segmentation which shows those areas in the image that surpass a minimum degree of smoothness. Though the msr has proven to be a very strong enhancement engine, the other elements of the approach|the vs, terrain map generation, and smoothness-based segmentation|are in early stages of development. Experimental results on data from the Mars Global Surveyor show that the imagery can be processed to automatically obtain smooth landing sites. In this paper, we describe the method used to obtain these landing sites, and also examine the smoothness criteria in terms of the imager and scene characteristics. Several examples of applying this method to simulated and real imagery are shown.

Rahman, Zia-ur↗
NASA NTRS2005

Photo-realistic Terrain Modeling and Visualization for Mars Exploration Rover Science Operations

Modern NASA planetary exploration missions employ complex systems of hardware and software managed by large teams of. engineers and scientists in order to study remote environments. The most complex and successful of these recent projects is the Mars Exploration Rover mission. The Computational Sciences Division at NASA Ames Research Center delivered a 30 visualization program, Viz, to the MER mission that provides an immersive, interactive environment for science analysis of the remote planetary surface. In addition, Ames provided the Athena Science Team with high-quality terrain reconstructions generated with the Ames Stereo-pipeline. The on-site support team for these software systems responded to unanticipated opportunities to generate 30 terrain models during the primary MER mission. This paper describes Viz, the Stereo-pipeline, and the experiences of the on-site team supporting the scientists at JPL during the primary MER mission.

Edwards, Laurence↗
NASA NTRS2006

To the North Coast of Devon: Collaborative Navigation While Exploring Unfamiliar Terrain

Navigation-knowing where one is and finding a safe route-is a fundamental aspect of all exploration. In unfamiliar terrain, one may use maps and instruments such as a compass or binoculars to assist, and people often collaborate in finding their way. This paper analyzes a group of people driving a humvee from a base camp to the north coast of Devon Island in the High Canadian Arctic. A complete audio recording and video during most stops allows a quantitative and semantic analysis of the conversations when the team stopped to take bearings and replan a route. Over a period of 2 hours, the humvee stopped 20 times, with an average duration of 3.15 min/pause and 3.85 min moving forward. The team failed to reach its goal due to difficult terrain causing mechanical problems. The analysis attempts to explain these facts by considering a variety of complicating factors, especially the navigation problem of relating maps and the world to locate the humvee and to plan a route. The analysis reveals patterns in topic structure and turn-taking, supporting the view that the collaboration was efficient, but the tools and information were inadequate for the task. This work is relevant for planning and training for planetary surface missions, as well as developing computer systems that could aid navigation.

Clancey, William J.↗
NASA NTRS2005

Vision guided landing of an an autonomous helicopter in hazardous terrain

Future robotic space missions will employ a precision soft-landing capability that will enable exploration of previously inaccessible sites that have strong scientific significance. To enable this capability, a fully autonomous onboard system that identifies and avoids hazardous features such as steep slopes and large rocks is required. Such a system will also provide greater functionality in unstructured terrain to unmanned aerial vehicles. This paper describes an algorithm for landing hazard avoidance based on images from a single moving camera. The core of the algorithm is an efficient application of structure from motion to generate a dense elevation map of the landing area. Hazards are then detected in this map and a safe landing site is selected. The algorithm has been implemented on an autonomous helicopter testbed and demonstrated four times resulting in the first autonomous landing of an unmanned helicopter in unknown and hazardous terrain.

Mars Landing↗
NASA NTRS2006

Automated On-board Terrain Analysis for Precision Landings

Advances in space robotics technology hinge to a large extent upon the development and deployment of sophisticated new vision-based methods for automated in-space mission operations and scientific survey. To this end, we have developed a new concept for automated terrain analysis that is based upon a generic image enhancement platform-multi-scale Retinex (MSR) and visual servo (VS) processing. This pre-conditioning with the MSR and the VS produces a "canonical" visual representation that is largely independent of lighting variations, and exposure errors. Enhanced imagery is then processed with a biologically inspired two-channel edge detection process, followed by a smoothness based criteria for image segmentation. Landing sites can be automatically determined by examining the results of the smoothness-based segmentation which shows those areas in the image that surpass a minimum degree of smoothness. Though the MSR has proven to be a very strong enhancement engine, the other elements of the approach, the VS, terrain map generation, and smoothness-based segmentation, are in early stages of development. Experimental results on data from the Mars Global Surveyor show that the imagery can be processed to automatically obtain smooth landing sites. In this paper, we describe the method used to obtain these landing sites, and also examine the smoothness criteria in terms of the imager and scene characteristics. Several examples of applying this method to simulated and real imagery are shown.

Rahman, Zia-ur↗
NASA NTRS2002

Interference from the Robledo DSN Transmitters to Central Madrid IMT-2000/UMTS System through Terrain Diffraction at S-Band

This study evaluates the possible interference from DSN Robledo 70-m transmitter with Madrid IMT-2000/UMTS wireless users in Spain as both systems will share the same frequency band. Using the effective earth radius, the 50 km terrain profile between Robledo and Madrid is modified and reconstructed. The diffraction propagation losses due to mountain peaks are calculated for the receivers in Madrid urban area. The mountains along the path are simplified into a rounded knife-edge and a rounded obstacle. The results show that for a near surface receiver (1.5 m above the ground) in Madrid, interference signal powers received are less than -135 dBm, which is far below the -109 dBm, the IMT-2000 wireless phone threshold. When a receiver is located at about 40 m above the ground (e.g., the top of Clock Tower of Cibeles Palace), diffraction will generate interference power less than -115 dBm. We find that our calculation results are basically consistent with those from the Longley-Rice model, while the latter has smaller loss because of the low resolution terrain profile used. As a comparison, we also find that the measurements of interference powers of -121.2 dBm at the top of Clock tower is in the range of the estimation. We conclude that the interference through the diffraction mechanism will not cause any problem to IMT-2000/UMTS users at near the surface of Madrid urban area.

telecommunications↗
NASA NTRS2006

Terrain-Moisture Classification Using GPS Surface-Reflected Signals

In this study we present a novel method of land surface classification using surface-reflected GPS signals in combination with digital imagery. Two GPS-derived classification features are merged with visible image data to create terrain-moisture (TM) classes, defined here as visibly identifiable terrain or landcover classes containing a surface/soil moisture component. As compared to using surface imagery alone, classification accuracy is significantly improved for a number of visible classes when adding the GPS-based signal features. Since the strength of the reflected GPS signal is proportional to the amount of moisture in the surface, use of these GPS features provides information about the surface that is not obtainable using visible wavelengths alone. Application areas include hydrology, precision agriculture, and wetlands mapping.

Grant, Michael S.↗
NASA NTRS2008

The Effects of Terrain and Navigation on Human Extravehicular Activity Walkback Performance on the Moon

Results of the EVA Walkback Test showed that 6 male astronauts were able to ambulate 10 km on a level treadmill while wearing a prototype EVA suit in simulated lunar gravity. However, the effects of lunar terrain, topography, and real-time navigation on ambulation performance are unknown. Primary objective: To characterize the effect of lunar-like terrain and navigation on VO2 and distance traveled during an unsuited 10 km (straight-line distance) ambulatory return in earth gravity.

Norcross, Jason↗
NASA NTRS2008

Terrain-Adaptive Navigation Architecture

A navigation system designed for a Mars rover has been designed to deal with rough terrain and/or potential slip when evaluating and executing paths. The system also can be used for any off-road, autonomous vehicles. The system enables vehicles to autonomously navigate different terrain challenges including dry river channel systems, putative shorelines, and gullies emanating from canyon walls. Several of the technologies within this innovation increase the navigation system s capabilities compared to earlier rover navigation algorithms.

Helmick, Daniel M.↗
NASA NTRS2010

Creation of High Resolution Terrain Models of Barringer Meteorite Crater (Meteor Crater) Using Photogrammetry and Terrestrial Laser Scanning Methods

Barringer Meteorite Crater or Meteor Crater, AZ, has been a site of high interest for lunar and Mars analog crater and terrain studies since the early days of the Apollo-Saturn program. It continues to be a site of exceptional interest to lunar, Mars, and other planetary crater and impact analog studies because of its relatively young age (est. 50 thousand years) and well-preserved structure. High resolution (2 meter to 1 decimeter) digital terrain models of Meteor Crater in whole or in part were created at NASA Stennis Space Center to support several lunar surface analog modeling activities using photogrammetric and ground based laser scanning techniques. The dataset created by this activity provides new and highly accurate 3D models of the inside slope of the crater as well as the downslope rock distribution of the western ejecta field. The data are presented to the science community for possible use in furthering studies of Meteor Crater and impact craters in general as well as its current near term lunar exploration use in providing a beneficial test model for lunar surface analog modeling and surface operation studies.

Brown, Richard B.↗
NASA NTRS2008

Mobile Lid Convection Beneath Enceladus' South Polar Terrain

Enceladus' south polar region has a large heat flux, 55-110 milliwatts per square meter (or higher), that is spatially associated with cryovolcanic and tectonic activity. Tidal dissipation and vigorous convection in the underlying ice shell are possible sources of heat; however, prior predictions of the heat flux carried by stagnant lid convection range from F(sub conv) ~15 to 30 milliwatts per square meter, too low to explain the observed heat flux. The high heat flux and increased cryovolcanic and tectonic activity suggest that near-surface ice in the region has become rheologically and mechanically weakened enough to permit convective plumes to reach close to the surface. If the yield strength of Enceladus' lithosphere is less than ~1-10 kPa, convection may instead occur in the mobile lid" regime, which is characterized by large heat fluxes and large horizontal velocities in the near-surface ice. I show that model ice shells with effective surface viscosities between 10(exp 16) and 10(exp 17) Pa s and basal viscosities between 10(exp 13) and 10(exp 15) Pa s have convective heat fluxes comparable to that observed by the Cassini Composite Infrared Spectrometer. If this style of convection is occurring, the south polar terrain should be spreading horizontally with v~1-10 millimeter per year and should be resurfaced in ~0.1-10 Ma. On the basis of Cassini imaging data, the south polar terrain is ~0.5 Ma old, consistent with the mobile lid hypothesis. Maxwell viscoelastic tidal dissipation in such ice shells is not capable of generating enough heat to balance convective heat transport. However, tidal heat may also be generated in the near-surface along faults as suggested by Nimmo et al. and/or viscous dissipation within the ice shell may occur by other processes not accounted for by the canonical Maxwell dissipation model.

Barr, Amy C.↗
NASA NTRS1964

Vehicle Walks on Varied Terrain, Can Assist Handicapped Persons

The problem: Designing a vehicle capable of traversing varied terrain at moderate speeds (up to 4 miles per hour). Development of such a vehicle was originally undertaken to meet NASA requirements for a remotely controlled instrument carrier to be used for unmanned exploration of lunar and planetary surfaces. The solution: A battery-powered motorized vehicle with three pairs of legs that are connected to push rods and a series of linkages. How it's done: Locomotion of the basic vehicle is accomplished by three pairs of legs, one pair in the front and two pairs in the rear. Each leg consists of an upper horizontal portion, a middle vertical portion, and a foot. Two cams connected to the drive mechanism (a small motor, gearbox, and push rods) control the motion of the legs. The two outer rear legs move in unison with the right front leg, and the two inner rear legs move in unison with the left front leg. Each set of three legs is lifted to clear or rest on any expected obstacle on the terrain to be traversed by the vehicle and advanced a fixed distance for the succeeding step. A system of spring-loaded vertical-motion linkages permits obstacles (within design limitations) to be traversed with a minimum disturbance of the vehicle's axes. The linkages are arranged to permit the legs to be folded when the vehicle is stored. Steering is accomplished by a small motor, which swings the front pair of legs to the desired angle. The rear legs are connected by a differential linkage to compensate for the required variation in step length or speed between the right and left pairs of rear legs when turns are made.

Source record↗
NASA NTRS2011

Evaluation of the Global Multi-Resolution Terrain Elevation Data 2010 (GMTED2010) Using ICESat Geodetic Control

Supported by NASA's Earth Surface and Interior (ESI) Program, we are producing a global set of Ground Control Points (GCPs) derived from the Ice, Cloud and land Elevation Satellite (ICESat) altimetry data. From February of 2003, to October of 2009, ICESat obtained nearly global measurements of land topography (+/- 86deg latitudes) with unprecedented accuracy, sampling the Earth's surface at discrete approx.50 m diameter laser footprints spaced 170 m along the altimetry profiles. We apply stringent editing to select the highest quality elevations, and use these GCPs to characterize and quantify spatially varying elevation biases in Digital Elevation Models (DEMs). In this paper, we present an evaluation of the soon to be released Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010). Elevation biases and error statistics have been analyzed as a function of land cover and relief. The GMTED2010 products are a large improvement over previous sources of elevation data at comparable resolutions. RMSEs for all products and terrain conditions are below 7 m and typically are about 4 m. The GMTED2010 products are biased upward with respect to the ICESat GCPs on average by approximately 3 m.

Carabajal, Claudia C.↗
NASA NTRS2006

Hybrid Terrain Database

A prototype hybrid terrain database is being developed in conjunction with other databases and with hardware and software that constitute subsystems of aerospace cockpit display systems (known in the art as synthetic vision systems) that generate images to increase pilots' situation awareness and eliminate poor visibility as a cause of aviation accidents. The basic idea is to provide a clear view of the world around an aircraft by displaying computer-generated imagery derived from an onboard database of terrain, obstacle, and airport information.

Arthur, Trey↗
NASA NTRS2005

Quantifying Traversability of Terrain for a Mobile Robot

A document presents an updated discussion on a method of autonomous navigation for a robotic vehicle navigating across rough terrain. The method involves, among other things, the use of a measure of traversability, denoted the fuzzy traversability index, which embodies the information about the slope and roughness of terrain obtained from analysis of images acquired by cameras mounted on the robot. The improvements presented in the report focus on the use of the fuzzy traversability index to generate a traversability map and a grid map for planning the safest path for the robot. Once grid traversability values have been computed, they are utilized for rejecting unsafe path segments and for computing a traversalcost function for ranking candidate paths, selected by a search algorithm, from a specified initial position to a specified final position. The output of the algorithm is a set of waypoints designating a path having a minimal-traversal cost.

Howard, Ayanna↗
NASA NTRS2005

Tool for Viewing Faults Under Terrain

Multi Surface Light Table (MSLT) is an interactive software tool that was developed in support of the QuakeSim project, which has created an earthquake- fault database and a set of earthquake- simulation software tools. MSLT visualizes the three-dimensional geometries of faults embedded below the terrain and animates time-varying simulations of stress and slip. The fault segments, represented as rectangular surfaces at dip angles, are organized into collections, that is, faults. An interface built into MSLT queries and retrieves fault definitions from the QuakeSim fault database. MSLT also reads time-varying output from one of the QuakeSim simulation tools, called "Virtual California." Stress intensity is represented by variations in color. Slips are represented by directional indicators on the fault segments. The magnitudes of the slips are represented by the duration of the directional indicators in time. The interactive controls in MSLT provide a virtual track-ball, pan and zoom, translucency adjustment, simulation playback, and simulation movie capture. In addition, geographical information on the fault segments and faults is displayed on text windows. Because of the extensive viewing controls, faults can be seen in relation to one another, and to the terrain. These relations can be realized in simulations. Correlated slips in parallel faults are visible in the playback of Virtual California simulations.

Siegel, Herbert, L.↗