Showing papers by "Jet Propulsion Laboratory published in 1997"
TL;DR: In this paper, the authors have estimated the current economic value of 17 ecosystem services for 16 biomes, based on published studies and a few original calculations, for the entire biosphere, the value (most of which is outside the market) is estimated to be in the range of US$16-54 trillion (10^(12)) per year, with an average of US $33 trillion per year.
Abstract: The services of ecological systems and the natural capital stocks that produce them are critical to the functioning of the Earth's life-support system. They contribute to human welfare, both directly and indirectly, and therefore represent part of the total economic value of the planet. We have estimated the current economic value of 17 ecosystem services for 16 biomes, based on published studies and a few original calculations. For the entire biosphere, the value (most of which is outside the market) is estimated to be in the range of US$16-54 trillion (10^(12)) per year, with an average of US$33 trillion per year. Because of the nature of the uncertainties, this must be considered a minimum estimate. Global gross national product total is around US$18 trillion per year.
18,139 citations
29 Jun 1997
TL;DR: In this article, the authors derived upper bounds to the average maximum likelihood bit error probability of serially concatenated block and convolutional codes with interleaver, and derived design guidelines for the outer and inner encoders that maximize the interleavers gain and the asymptotic slope of the error probability curves.
Abstract: A serially concatenated code with interleaver consists of the cascade of an outer encoder, an interleaver permuting the outer codewords bits, and an inner encoder whose input words are the permuted outer codewords. The construction can be generalized to h cascaded encoders separated by h-1 interleavers. We obtain upper bounds to the average maximum-likelihood bit error probability of serially concatenated block and convolutional coding schemes. Then, we derive design guidelines for the outer and inner encoders that maximize the interleaver gain and the asymptotic slope of the error probability curves. Finally, we propose a new, low-complexity iterative decoding algorithm. Throughout the paper, extensive comparisons with parallel concatenated convolutional codes known as "turbo codes" are performed, showing that the new scheme can offer superior performance.
1,361 citations
TL;DR: Several broad emission features observed in the 7- to 45-micrometer region suggest the presence of silicates, particularly magnesium-rich crystalline olivine, similar to those observed inThe dust envelopes of Vega-type stars.
Abstract: Comet Hale-Bopp (C/1995 O1) was observed at wavelengths from 2.4 to 195 micrometers with the Infrared Space Observatory when the comet was about 2.9 astronomical units (AU) from the sun. The main observed volatiles that sublimated from the nucleus ices were water, carbon monoxide, and carbon dioxide in a ratio (by number) of 10:6:2. These species are also the main observed constituents of ices in dense interstellar molecular clouds; this observation strengthens the links between cometary and interstellar material. Several broad emission features observed in the 7- to 45-micrometer region suggest the presence of silicates, particularly magnesium-rich crystalline olivine. These features are similar to those observed in the dust envelopes of Vega-type stars.
491 citations
TL;DR: In this article, an optical-IR photometric study of early-type galaxies in 19 galaxy clusters out to z = 0.9 was performed, showing that the color evolution of the early type galaxies becomes bluer with increasing redshift, consistent with the passive evolution of an old stellar population formed at an early cosmic epoch.
Abstract: We present results from an optical-IR photometric study of early-type galaxies in 19 galaxy clusters out to z=0.9. The galaxy sample is selected on the basis of morphologies determined from HST WFPC2 images, and is photometrically defined in the K-band to minimize redshift-dependent selection biases. The optical-IR colors of the early-type cluster galaxies become bluer with increasing redshift in a manner consistent with the passive evolution of an old stellar population formed at an early cosmic epoch. The degree of color evolution is similar for clusters at similar redshift, and does not depend strongly on the optical richness or X-ray luminosity of the cluster, suggesting that the history of early-type galaxies is relatively insensitive to environment. The slope of the color-magnitude relationship shows no significant change out to z=0.9, providing evidence that it arises from a correlation between galaxy mass and metallicity, not age. Finally, the intrinsic scatter in the optical-IR colors is small and nearly constant with redshift, indicating that the majority of giant, early-type galaxies in clusters share a common star formation history, with little perturbation due to uncorrelated episodes of later star formation. Taken together, our results are consistent with models in which most early-type galaxies in rich clusters are old, formed the majority of their stars at high redshift in a well-synchronized fashion, and evolved quiescently thereafter.
422 citations
TL;DR: In this article, the authors explore the origin of these distinct GC populations, the implications for galaxy formation and evolution, and identify several new properties of GC systems, and conclude that the gaseous merger model of Ashman & Zepf (1992) is correct.
Abstract: Perhaps the most noteworthy of recent findings in extragalactic globular cluster (GC) research are the multimodal GC metallicity distributions seen in massive early-type galaxies. We explore the origin of these distinct GC populations, the implications for galaxy formation and evolution, and identify several new properties of GC systems. First, when we separate the metal-rich and metal-poor subpopulations, in galaxies with bimodal GC metallicity distributions, we find that the mean metallicity of the metal-rich GCs correlates well with parent galaxy luminosity but the mean metallicity of the metal-poor ones does not. This indicates that the metal-rich GCs are closely coupled to the galaxy and share a common chemical enrichment history with the galaxy field stars. The mean metallicity of the metal-poor population is largely independent of the galaxy luminosity. Second, the slope of the GC system radial surface density varies considerably in early-type galaxies. However the galaxies with relatively populous GC systems for their luminosity (called high specific frequency, S_N) only have shallow, extended radial distributions. A characteristic of high S_N galaxies is that their GCs are preferentially located in the outer galaxy regions relative to the underlying starlight. Third, we find that the ratio of metal-rich to metal-poor GCs correlates with S_N. In other words, high S_N galaxies have proportionately more metal-poor GCs, per unit galaxy light, than low S_N galaxies. Fourth, we find steeper metallicity gradients in high S_N galaxies. This is due to the greater number of metal-poor GCs at large galactocentric radii. We critically review current ideas for the origin of GCs in giant elliptical (gE) and cD galaxies and conclude that the gaseous merger model of Ashman & Zepf (1992) is
368 citations
TL;DR: The Configuration Description Language (CDL) is developed to capture the recursive composition of configurations in an architecture- and robot-independent fashion and the Societal Agent theory is presented as a basis for constructions of this form.
Abstract: Specifying a reactive behavioral configuration for use by a multiagent team requires both a careful choice of the behavior set and the creation of a temporal chain of behaviors which executes the mission. This difficult task is simplified by applying an object-oriented approach to the design of the mission using a construction called an assemblage and a methodology called temporal sequencing. The assemblage construct allows building high level primitives which provide abstractions for the designer. Assemblages consist of groups of basic behaviors and coordination mechanisms that allow the group to be treated as a new coherent behavior. Upon instantiation, the assemblage is parameterized based on the specific mission requirements. Assemblages can be re-parameterized and used in other states within a mission or archived as high level primitives for use in subsequent projects. Temporal sequencing partitions the mission into discrete operating states with perceptual triggers causing transitions between those states. Several smaller independent configurations (assemblages) can then be created which each implement one state. The Societal Agent theory is presented as a basis for constructions of this form. The Configuration Description Language (CDL) is developed to capture the recursive composition of configurations in an architecture- and robot-independent fashion. The MissionLab system, an implementation based on CDL, supports the graphical construction of configurations using a visual editor. Various multiagent missions are demonstrated in simulation and on our Denning robots using these tools.
282 citations
TL;DR: In this article, the authors apply Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data to the monitoring of seasonal changes in atinospheric water vapor, liquid water, and surface cover in the vicinity of the Jasper Ridge, CA, for three dates in 1992.
246 citations
TL;DR: In this paper, the authors applied dynamical systems theory to better understand the geometry of the phase space in the three-body problem via stable and unstable manifolds, which were used to generate various solution arcs and establish trajectory options that were then utilized in preliminary design for the proposed Suess-Urey mission.
Abstract: Recently, there has been accelerated interest in missions utilizing trajectories near libration points. The trajectory design issues involved in missions of such complexity go beyond the lack of preliminary baseline trajectories (since conic analysis fails in this region of the solution space). Successful and efficient design of mission options will require new persepectives; a more complete understanding of the solution space is imperative. In this investigation, dynamical systems theory is applied to better understand the geometry of the phase space in the three-body problem via stable and unstable manifolds. Then, the manifolds are used to generate various solution arcs and establish trajectory options that are then utilized in preliminary design for the proposed Suess-Urey mission.
225 citations
TL;DR: The potential of SAR interferometric techniques for the retrieval of vegetation parameters was investigated using ERS-1 data over agricultural and forested test sites and it was possible to identify harvesting by the high correlation of the post-harvest bare or stubble field.
Abstract: The potential of SAR interferometric techniques for the retrieval of vegetation parameters was investigated using ERS-1 data over agricultural and forested test sites. In a first experiment an interferometrically derived forest map was generated. The classification was based on the interferometric correlation and the backscatter intensities. The result was geocoded, using the interferometrically derived height map generated from the same ERS SAR data pair, and validated with a conventional digital forest map. Forest mapping accuracies of around 90% and better were achieved. In a second experiment, multitemporal data over an agricultural site were used to investigate the potential of repeat-pass interferometry to monitor farming activity, crop development, and soil moisture variations. The interferometric correlation was used as an indicator of dense vegetation and geometric change. It was possible, for example, to identify harvesting by the high correlation of the post-harvest bare or stubble field. Decreasing interferometric correlation was observed as a consequence of crop growth.
219 citations
TL;DR: In this paper, a monolithic array oscillators incorporating Schottky-collector resonant tunnel diodes (SRTDs) were reported, achieving a 2.2 THz maximum frequency of oscillation.
Abstract: We report monolithic array oscillators incorporating Schottky-collector resonant tunnel diodes (SRTD's). In the SRTD, a 0.1-/spl mu/m width Schottky collector contact provides a greatly reduced device series resistance, resulting in an estimated 2.2 THz maximum frequency of oscillation. A 64-element oscillator array oscillated at 650 GHz while a 16-element array produced 28 /spl mu/W at 290 GHz.
169 citations
TL;DR: In this paper, the authors applied the finite-difference time-domain (FDTD) method to calculate the resonant frequency of dielectric resonators with curved surface, and compared with theoretical values and staircase approximation, and show that the present method is more accurate than the staircase approximation.
Abstract: In this paper, the finite-difference time-domain (FDTD) method is applied to calculate the resonant frequency of dielectric resonators (DRs) with curved surface. The contour-path integral FDTD (CFDTD) is modified to deal with the curved surface of the dielectric body while the traditional rectangular cells are maintained. Results are compared with theoretical values and staircase approximation, and show that the present method is more accurate than the staircase approximation.
TL;DR: In this paper, a velocity-matched distributed photodetector (VMDP) is proposed to achieve high saturation photocurrent and broad bandwidth simultaneously, and a comprehensive theoretical model has been developed for the design and simulation of the VMDP.
Abstract: A novel velocity-matched distributed photodetector (VMDP) is proposed to simultaneously achieve high saturation photocurrent and broad bandwidth. Theoretical analysis on the tradeoff between saturation power and bandwidth shows that the VMDP offers fundamental advantages over conventional photodetectors. A comprehensive theoretical model has been developed for the design and simulation of the VMDP. Experimentally, the VMDP with very high saturation (56-mA) photocurrent and instrument-limited 3-dB bandwidth (49 GHz) has been demonstrated. The theoretical analysis and experimental results show that the VMDP is very attractive for high-performance microwave photonic links and high-power optical microwave applications.
TL;DR: In this paper, the magnetic field measured during the second pass by Ganymede, with closest approach at low altitude almost directly over the moon's polar cap, can be understood to a large measure in terms of the structure of a vacuum superposition model of a uniform field.
Abstract: Within Jupiter's magnetosphere, Ganymede's magnetic field creates a mini-magnetosphere. We show that the magnetic field measured during Galileo‧s second pass by Ganymede, with closest approach at low altitude almost directly over the moon's polar cap, can be understood to a large measure in terms of the structure of a vacuum superposition model of a uniform field and a Ganymede-centered dipole field. Departures from the simple model can be attributed principally to magnetopause currents. We show that the orientation of the observed magnetopause normal is qualitatively consistent with expectations from the vacuum superposition model. The magnetopause currents inferred from the inbound boundary crossing are closely related to expected values, and the magnetic structure of the boundary is similar to that observed at the magnetopause of Earth. We use the vacuum magnetic field model to infer the magnetic field near Ganymede's surface, and thereby predict the particle loss cones that should be present along the spacecraft trajectory. By mapping a fraction of the corotation electric field into the polar cap, we determine expected flow velocities near closest approach to Ganymede as a function of reconnection efficiency. We conclude by discussing prospects for measurements on Galileo's remaining passes by Ganymede.
TL;DR: In this paper, the authors present a coordinated study of one of the events which occurred near 6.03Rj just after 17:34 UT on December 7, 1995, which is interpreted as the first evidence for the predicted interchange motions in the region exterior to the orbit of I o.
Abstract: Anomalous plasma signatures were detected by the Galileo particles and fields instruments during the initial transit through the Io torus. These unusual events are characterized by abrupt changes in the magnetic field, enhanced levels of broadband low frequency electromagnetic waves and a pronounced change in both the flux and pitch angle anisotropy of energetic particles. Here we present a coordinated study of one of the events which occurred near 6.03Rj just after 17:34 UT on December 7, 1995. The available data are consistent with the concept of rapid inward transport, and this is interpreted as the first evidence for the predicted interchange motions in the region exterior to the orbit of I o. Theoretical arguments indicate that the interchanging flux tube is characterized by substantially reduced plasma density, a spatial scale comparable to 10 3 km, and an inward radial velocity comparable to 102 km/s.
TL;DR: A simple, approximate method for the recalculation of asteroid diameters and geometric albedos given new, improved absolute visual magnitudes was presented by Tedesco et al..
TL;DR: The water hypothesis was strengthened by the presence of a shore-like contact between smooth-surfaced deposits and ancient cratered terrain in central Sinus Meridiani, polygonal structures in northern Sinus meridiani, and sand (which cannot be from airfall), possibly reworked by wind from the underlying sedimentary units as mentioned in this paper.
Abstract: Western Arabia and northern Sinus Meridiani (30°N–10°S; 40°W–40°E) are almost entirely covered by wind-eroded, horizontally-bedded, sedimentary layers that lap against local topographic features. This portion of Mars' ancient cratered terrain is relatively low (< 1 km elevation) and flat (sloping westward 0.7 m/km over 3,000 km). The region lacks valley network channels. We propose that at some time in early Martian history, this region was under water. The water hypothesis is strengthened by the presence of (1) a shore-like contact between smooth-surfaced deposits and ancient cratered terrain in central Sinus Meridiani, (2) polygonal structures in northern Sinus Meridiani, and (3) sand (which cannot be from airfall), possibly reworked by wind from the underlying sedimentary units. The September 1997 arrival of Mars Global Surveyor's thermal emission spectrometer offers an opportunity to begin to test this hypothesis by searching for carbonate and evaporite minerals among the sediment covering the region.
TL;DR: In this article, a new model is developed based on J. Geophys. Res. 98, 17029-17048, Divine's (1993, ''five populations of interplanetary meteoroids'' model.
01 Oct 1997
TL;DR: This paper considers the purposes that exemplars may serve, and explores the incompatibilities inherent in trying to serve several of them at once, and examines the use of exemplars not only for writing specifications, but also for the requirements engineering process itself.
Abstract: Specification exemplars are familiar to most software engineering researchers. For instance, many will have encountered the well known library and lift problem statements, and will have seen one or more published specifications. Exemplars may serve several purposes: to drive and communicate individual research advances; to establish research agendas and to compare and contrast alternative approaches; and, ultimately, to lead to advances in software development practices.
Because of their prevalence in the literature, exemplars are worth critical study. In this paper we consider the purposes that exemplars may serve, and explore the incompatibilities inherent in trying to serve several of them at once. Researchers should therefore be clear about what successfully handling an exemplar demonstrates. We go on to examine the use of exemplars not only for writing specifications (an end product of requirements engineering), but also for the requirements engineering process itself. In particular, requirements for good requirements exemplars are suggested and ways of obtaining such exemplars are discussed.
TL;DR: In this article, the authors reported the discovery of a galaxy cluster at z=1.27, which is the highest red-shift cluster without targetting a central active galaxy.
Abstract: We report the discovery of a galaxy cluster at z=1.27. ClG J0848+4453 was found in a near-IR field survey as a high density region of objects with very red J-K colors. Optical spectroscopy of a limited number of 24 < R < 25 objects in the area shows that 6 galaxies within a 90 arcsec (0.49/h Mpc, q_O = 0.1) diameter region lie at z=1.273 +/- 0.002. Most of these 6 member galaxies have broad-band colors consistent with the expected spectral energy distribution of a passively-evolving elliptical galaxy formed at high redshift. An additional 2 galaxies located ~2 arcmin from the cluster center are also at z=1.27. Using all 8 of these spectroscopic members, we estimate the velocity dispersion is 700 +/- 180 km/s, similar to that of Abell R=1 clusters in the present epoch. A deep Rosat PSPC observation detects X-ray emission at the 5 sigma level coincident with the nominal cluster center. Assuming that the X-ray flux is emitted by hot gas trapped in the potential well of a collapsed system (no AGN is known to exist in the area), the resulting X-ray luminosity in the rest frame 0.1-2.4 keV band of L_x = 1.5 x 10^44 ergs/s suggests the presence of a moderately large mass. ClG J0848+4453 is the highest redshift cluster found without targetting a central active galaxy.
TL;DR: In this article, the authors studied how astrophysical jets are formed and the evolution of such phenomena as active galactic nuclei and quasars, Galactic superluminal x-ray sources, and young stellar objects.
Abstract: Understanding how astrophysical jets are formed is important for understanding the nature and evolution of such phenomena as active galactic nuclei and quasars, Galactic superluminal x-ray sources, and young stellar objects.
TL;DR: The first radio occultation measurements of the ionosphere of Jupiter were performed by the Galileo spacecraft as mentioned in this paper, which passed behind the planet on December 8, 1995, allowing the first Radio Occlusion measurements of its ionospheric structure in 16 years.
Abstract: The Galileo spacecraft passed behind Jupiter on December 8, 1995, allowing the first radio occultation measurements of its ionospheric structure in 16 years. At ingress (24°S, 68°W), the principal peak of electron density is located at an altitude of 900 km above the 1-bar pressure level, with a peak density of 105 cm−3 and a thickness of ∼200 km. At egress (43°S, 28°W), the main peak is centered near 2000 km altitude, with a peak density of 2×104 cm−3 and a thickness of ∼1000 km. Two thin layers, possibly forced by upwardly propagating gravity waves, appear at lower altitudes in the ingress profile. This is the first in a two-year series of observations that should help to resolve long-standing questions about Jupiter's ionosphere.
TL;DR: In this article, a C language computer program is used to compute the gravitational potential of a constant-density polyhedron with respect to a constant number of spherical harmonic coefficients C n, m and S n, m.
TL;DR: The TOPEX/POSEIDON satellite altimeter mission has measured sea level on a global basis over the last 4 years at 10 day intervals as discussed by the authors, and after correcting for a recently discovered error in the measurements, the estimated rate of global mean sea level change over this time period is −0.2 mm/year.
Abstract: The TOPEX/POSEIDON satellite altimeter mission has measured sea level on a global basis over the last 4 years at 10 day intervals. After correcting for a recently discovered error in the measurements, the estimated rate of global mean sea level change over this time period is −0.2 mm/year. Comparisons to tide gauge sea levels measured in spatial and temporal proximity to the satellite measurements suggest there is a residual drift in the satellite measurement system of −2.3±1.2 mm/year, the origin of which is presently unknown. Application of this rate correction yields a “calibrated” estimate of +2.1±1.3 mm/year for the rate of sea level rise, which agrees statistically with tide gauge observations of sea level change over the last 50 years. Since the contribution of interannual and decadal mean sea level variations cannot presently be isolated, a longer time series is required before long-term climate change signals can be detected. In addition, an improved understanding of the T/P measurement system performance with time is needed.
TL;DR: In this paper, a hardness assurance test approach for bipolar linear circuits and devices in space is developed for bipolar circuits and they use a characterization test method to develop the conditions for a lot acceptance test at high dose rate.
Abstract: A hardness assurance test approach has been developed for bipolar linear circuits and devices in space. It consists of an initial test for dose rate sensitivity and a characterization test method to develop the conditions for a lot acceptance test at high dose rate. For parts with adequate design margin and/or well behaved parts a generic elevated temperature irradiation test is proposed.
TL;DR: In this paper, a physical model of the atmospheric boundary layer and regolith can produce a nighttime depletion of this magnitude by diffusion of water into the regolith and adsorption onto regolith grains.
TL;DR: In this article, the authors presented observations of 125 asteroids taken by traditional photoelectric photometry as well as with CCD imaging systems, from 1985 to the end of 1993, just 2 months before the untimely death of the first author.
TL;DR: In this paper, the binary frequency for optically visible (IHST < 19 mag) members of the dense embedded stellar clusters associated with NGC 2024, NGC 2068, and NGC2071 (distance = 460 pc) based on Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) observations is estimated.
Abstract: We present estimates of the binary frequency for optically visible (IHST < 19 mag) members of the dense (mean star separation ~0.05 pc) embedded stellar clusters associated with NGC 2024, NGC 2068, and NGC 2071 (distance = 460 pc) based on Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) observations. Of 99 targets, 15 are found to be double stars with projected linear separations of 138-1050 AU (03 < θ < 23). The resulting multiplicity fraction is 15/99 or 0.15 ± 0.04 in this separation range, while the comparable values observed for solar neighborhood G and K stars are 0.11 and 0.09, respectively. We also examined the archival F547M WFPC2 images of the Trapezium cluster obtained by O'Dell & Wen and found a binary frequency of 7/50 or 0.14 ± 0.05 in the separation range 138-828 AU for stars with VHST < 17. Our results compare well with the value of 0.16 ± 0.03 determined recently by Reipurth & Zinnecker from observations of 238 pre-main-sequence (PMS) stars in nearby (d ~ 150 pc) low-density (mean star separation ~0.3 pc) star-forming regions over comparable separation ranges. Our results suggest an excess of PMS binaries over main-sequence binaries with the same separations. In addition, we find no evidence that the fraction of binaries formed in relatively dense clusters differs from that characterizing low-density star-forming regions.
TL;DR: The second encounter of the Galileo satellite with the Galilean moon Ganymede provided energetic particle measurements showing effects due to the presence of that moon as mentioned in this paper, where the Energetic Particles Detector (EPD) views along the magnetic field line.
Abstract: The second encounter of the Galileo satellite with the Galilean moon Ganymede provided energetic particle measurements showing effects due to the presence of that moon. Jovian corotation signatures, present on approach to and departure from the Ganymede system, suddenly become much smaller when Galileo enters what has been termed Ganymede's magnetosphere. The location of these transitions agrees with magnetopause crossings identified by the magnetometer and plasma wave instruments. In Ganymede's magnetosphere, energetic ion and electron distributions display loss cone signatures whenever the Energetic Particles Detector (EPD) views along the magnetic field line. The loss cone measurements are used to estimate Ganymede's surface magnetic field along the satellite track. The results agree with model projections to Ganymede's polar cap and support the existence of a Ganymede-intrinsic magnetic field. An evolution from single to double loss cone also occurs with increasing electron energy.
TL;DR: In this paper, during the Galileo inbound pass through the Io torus, the plasma wave instrument detected intervals of enhanced whistler-mode emissions, which were interpreted as a modulation of cyclotron whistlermode instability above the normal marginally stable state of the plasma.
Abstract: During the Galileo inbound pass through the Io torus the plasma wave instrument detected intervals of enhanced whistler-mode emissions. Over two of these intervals in the inner torus (L < 6.5), for which energetic particle data is also available, the flux and pitch angle anisotropy of resonant electrons exhibited a simultaneous enhancement consistent with inward adiabatic transport from a source region in the outer torus. The enhanced electromagnetic emissions are interpreted as a modulation of cyclotron whistler-mode instability above the normal marginally stable state of the plasma. This suggests that the enhanced emissions are a sensitive indicator of rapid inward transport associated with interchange motions in the Io torus.
17 Jun 1997
TL;DR: An in-depth analysis of the major error sources for such a real-time stereo system in the contest of cross-country navigation of an autonomous vehicle shows that the precision of the stereo algorithm can be improved by 50%.
Abstract: Correlation-based real-time stereo systems have been proven to be effective in applications such as robot navigation, elevation map building etc. This paper provides an in-depth analysis of the major error sources for such a real-time stereo system in the contest of cross-country navigation of an autonomous vehicle. Three major types of errors: foreshortening error, misalignment error and systematic error are identified. The combined disparity errors can easily exceed three-tenths of a pixel, which translates to significant range errors. Upon understanding these error sources, we demonstrate different approaches to either correct them or model their magnitudes without excessive additional computations. By correcting those errors, we show that the precision of the stereo algorithm can be improved by 50%.