Topography System

[Algernon Alcala]

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Purpose: The corneal horizontal diameter (white-to-white) is abnormal in diseases like microcornea, relative anterior microphthalmos, and corneal dystrophies. Because normal values are described imprecisely in the literature, the purpose of this study was to reevaluate the horizontal corneal diameter as a scientific parameter.

Methods: The horizontal corneal diameter was measured with the Orbscan II system in 370 right eyes and 373 left eyes of 390 healthy white subjects aged 10-80 years. There were 148 female subjects and 242 male subjects. Each measurement was repeated twice. Differences in gender, between right and left eyes, and age-related alterations were analyzed statistically.

Conclusions: With the obtained normal values, more precise determination of microcornea and macrocornea will be possible in the future. The horizontal corneal diameter was not significantly greater in males than in females. Further studies are needed to show the reasons for the age-related decrease in measurements.

You will be directed to the NASA Visible Earth webpage when you select Images by Mission below, or click on the images at right that are randomly generated to represent four out of all possible topics.

The Ocean Surface Topography Mission (OSTM), a continuation of the TOPEX/Poseidon and Jason missions, is based on the science and pre-operational returns of these two missions and will support global and regional operational applications. Like its predecessors, OSTM will map ocean surface topography and the data collected will provide information on ocean surface current velocity and heights which, when combined with ocean models, can lead to a four-dimensional description of ocean circulation. Data from OSTM will extend the time series of ocean surface topography measurements for detecting previously unknown changes on decadal scales, increase understanding of ocean circulation, improve forecasting of climate events, and measure global sea level change.

The HTG-1 Full Corneal Topography System is a specialized solution for comprehensive corneal topography analysis, offering the most reliable and precise corneal information. This high-accuracy corneal data supports diagnosis and monitoring of various corneal conditions, refractive power variations, irregular astigmatism, keratoconus, and more.

HTG-1 measures the curvature, pupil, and corneal aberration data which are then presented in various maps and graphs. These results are dependable in assessing refractive status and guiding cataract surgery.

Placido disc analysis technology allows precise measurement of various corneal data including Keratometry, Topography, Keratoconus, Zernike Coefficients, Pupillometry, and white-to-white measurements.

The resulting data is presented in the form of Axial, Tangential, Refractive Power, and Elevation Maps. This information is invaluable for assessing the shape and health status of the cornea, determining vision correction lens prescriptions, and planning for cataract surgery.

Through the analysis of Zernike Coefficients/Map, HTG-1 measures and provides analysis data for various parameters including refractive power variations, irregular astigmatism, and aberrations in the eye.

Pupil size and responsiveness are evaluated under various lighting conditions, both day and night. Results are graphically displayed including pupil diameter, maximum average pupil diameter, and average pupil diameter.

Automatic measurements of corneal size, essential for diagnosing and monitoring a range of eye conditions such as congenital glaucoma, cataract and refractive surgery planning, and selection and fitting of contact lenses. Measurement data can be easily adjusted and applied using the Edit function.

A simulator accurately replicates the fitting results for both Hard Contact Lenses and Soft Contact Lenses using the Fluorescein Image Filter, all without the need for direct injection of fluorescent liquids.

The proposed work is to investigate and develop a novel, accurate, and low-cost system for structural 3Dimaging and comparison of cartridge casings and to demonstrate the system's potential for increasingthe quality and reducing the cost of forensic analyses. Despite the importance of tool mark analysis inthe forensic sciences, the imaging and comparison of tool marks remains a difficult and time consumingendeavor. Cartridge case comparison is based on the observation that microscopic firearm imperfections(such as those on a breech-face) can be transferred to a fired cartridge case. Therefore, two cases withhighly similar breech-face impressions are likely to have been fired through the same firearm. The abilityto certify two cases as highly similar is therefore a function of both the ability to capture a high-resolutionmeasurement of each case and the ability to identify and match relevant structural features.

The next generation of methods for the forensic analysis of tool marks should improve accuracy,reduce acquisition and operational costs, and shorten analysis time. Our platform utilizes the recentlydeveloped GelSight surface topography imaging system and custom feature-based image comparisonsoftware. Compared to competing technologies, our 3D GelSight-based system is fast, inexpensive, andnot sensitive to the optical properties of the material being measured. In collaboration with forensicsexperts, we proposed to improve our hardware and software, conduct several moderate scale experimentalbenchmarks, and deploy system prototypes. These are critical steps towards the development of alow-cost, fast, and accurate next generation system for cartridge case comparison and database search.

Through this award we completed several important goals. We completed the research and designprocess and advanced our prototype scanner and casing analysis algorithms to the level where they cannow be used in larger research studies and can be deployed to collaborating labs. We demonstrated thatour GelSight-based imaging system is able to capture the three-dimensional surface topographies of cartridgecases at high resolution. We tested our imaging and analysis system using several experimentaldatasets. The results demonstrate the system's current performance on real-world casings (including welland poorly marked casings). We achieve excellent performance on good marking casings and surprisinglygood performance on extremely challenging casings, casings that a firearms expert claims wouldbe difficult and time consuming to match. Most importantly, there are no false-positives across approximately200,000 comparisons. We also evaluated our system using a test set of clean, well marked testfires. We achieve even better performance with these clean casings.

In summary, we have redesigned the base scanner, designed and machined a fully functional cartridgecase mount, achieved excellent performance across three experimental datasets, created software whichallows 3D visualization of cartridge casings and database search, deployed our hardware and softwaresystem to several forensics labs, and we assembled a large experimental set of test fires. These resultsall strongly support the goals of the proposed study. We have demonstrated a novel technique for theimaging and analysis of cartridge casings and we have shown excellent performance compared to thestate-of-the-art alternatives.

Topography and landscape position are the first things seen when the site is visited. In the broadest sense, topography describes the physical features of the land surface, including relative elevations and the aspect of the surface. Landscape position describes the location of the site relative to the location on a slope.

The characteristics of the topography and landscape position influence the way that water moves both on and within the soil. For example, the site may be at the top (summit) or the bottom (toe) of a slope. This determines the nature of surface water movement. The upslope portions of the landscape have good external drainage as water flows away from them. The lower areas have poor external drainage as water flows into them.

The shape of the slope is another important characteristic that predicts water movement on the site. The slope description describes the land surface along and perpendicular to the slope using terms of planer/linear, convex and concave. This information is useful in determining surface and subsurface drainage patterns. For example, sloping convex areas typically have good surface and subsurface drainage away from the area, while concave sloping areas such as potholes, drainage ways, and foot slopes are more likely to possess wetter soil conditions.

If the proposed wastewater treatment area is located at the bottom of a concave type landscape where water flows to one common area, the design should include precautions if the system could not be relocated to an area of less surface water flow. Some of these precautions may include surface water redirection by means of berms and swales to route the surface water around the onsite wastewater treatment system.

Groundwater also moves toward a common area in concave slopes and can raise the seasonal high groundwater table in these areas relative to the rest of the parcel of land. When excavating in these areas, the installer must be careful in assessing if the observed seasonal high groundwater table agrees with the site and soil evaluation report.

Topography and landscape can affect all activities related to the installation. If a site has drainage issues, the timing of the installation may have to be adjusted on the basis of weather delays. Temporary drainage may be needed for access to the installation area or to protect adjacent property. Equipment selection may also be affected. Staging areas must be carefully chosen to ensure access. Sediment and erosion control measures may be required.

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