The performance of systems for on-line triangulation as well as for real-time point positioning depends on both effective hardware and software. Full utilization of the potential provided by the hardware, always depends on effective software. In this context there is an on-going search for fast algorithms for sequential adjustment. The performance of such algorithms can best be judged by practical tests using software which is as close as possible to the real application. This paper discusses an algorithm based on Givens transformations, and includes the results of a comparative test of this algorithm and the Triangular Factor Update. In the test, the Givens transformations algorithm appears to be up to four times faster than the Triangular Factor Update for updating the factorized normal equation system.
The High-Resolution Imaging Spectrometer (HIRIS) is a JPL-facility instrument designed for NASA's Earth Observing System (Eos). It will have 10-nm wide spectral bands from 0.4 to 2.5 μm at 30-m spatial resolution over a 24-km swath. The spectral resolution allows identification of many minerals in rocks and soils, important algal pigments in oceans and inland waters, spectral changes associated with plant canopy biochemistry, composition of atmospheric aerosols, and grain size of snow and its contamination by absorbing impurities. The bands will have 12-bit quantization over a dynamic range suitable for bright targets, such as snow. For targets of low brightness, such as water bodies, image-motion compensation will allow gains up to a factor of 8 to increase signal-to-noise ratios. The sensor will be able to point ±26° crosstrack and +52°/−30° downtrack. In the 705-km orbit altitude proposed for Eos, the crosstrack pointing capability will allow 3–4 views during a 16-day revisit cycle.
In quality analysis, optimization design and blunder detection of many photogrammetric problems, repeated computation of reliability matrix QvvP is often required. In this paper, a new recursive method for repeated computation of QvvP is developed. From a test on a bundle block adjustment, it is shown that this new method posesses much higher computational efficiency than the conventional methods.
The objective of this paper is to show how a sequence of elementary morphological filtering operations can lead to the correction of the stripping effect present on some level 1B SPOT images. The basic idea employed is to design the morphological filter using an a priori modeling of the stripes. The overall algorithm is divided in three steps. A binary image showing the high frequencies in the vertical direction is first obtained. Another binary image is then deduced which indicates the location of the stripes. Finally, the corrected image is obtained by morphological interpolation at the stripe location. The effect of each processing step is illustrated from an original image of the Porto Alegre city, south of Brazil, corrupted by the stripes.
Crop biomass can be evaluated from radiometric measurements either by relating biomass to instantaneous measurements or by relating an integral of biomass to a radiometric value integrated over the corresponding portion of the growth period.
A conceptually parallel road detection method in Landsat 4 TM images is proposed. The goal is to detect roads at three different levels: major roads, local roads, and minor roads. This road network information is used for the evaluation of detected potential oil/gas pads, since these pads seldom occur on major roads but are often located at the end of minor access roads.
In a bundle adjustment, the imaging configuration is an important factor in computing the accuracy of the object points. The theory of optimizing network configuration is applied to photogrammetry. For application to imaging, camera stations are shifted in order to improve the precision of object-point determination by improved intersections of rays. A criterion matrix is used as a target function in the optimization process. This matrix is constructed as an ideal covariance matrix that demands homogeneous and isotropic errors. The optimization process approximates the real covariance matrix of the network to the ideal criterion matrix by means of small shifts of the camera stations. The approximation is performed by a least-squares process which minimizes the discrepancies between the real covariance matrix of a given starting configuration, and an ideal, constructed criterion matrix.
In recent years, proximal sensing data has increasingly been used to optimize forest inventories. In this paper we present a forest inventory methodology based on stereoscopic hemispherical images. An automated pixel-based approach and a user-guided “region growing” approach have been developed for image matching. To estimate the basal area, number of trees and mean diameter, the sampling probability is determined for each tree. The accuracy and precision of the estimates derived from stereoscopic hemispherical images was analyzed for a set of National Forest Inventory plots. The results revealed that tree matching depends on the species, the distance to the target tree and the diameter. The Pearson correlation coefficient was 0.86 for the mean diameter and 0.89 for the basal area, whereas for the number of trees per hectare it was 0.59. The proposed methods may be used in large scale forest inventories as a cost-efficient way of obtaining data on diameter distribution and basal area from field surveys following a two-stage scheme combined with remote sensing techniques.
The economy of X-ray photogrammetry systems is analyzed first as a geometrical economy where a maximum accuracy should be achieved with a minimum radiation through proper geometry. Experiments for the various geometry are discussed and illustrated. Second, the system is analyzed for data processing. Possible automation and computer programs are discussed. A desirable data flow is presented with proper hardware configuration.
Today, digital mapping is the method for production of large-scale maps in Denmark, and it is used in all the private mapping companies working for municipalities and utility companies. The rapid introduction of the modern technology is a result of the introduction of the use of natural gas all over the country. This project was financially big enough, and the technology for digital mapping was at a breaking point, so these two factors together made the change possible. The development of a data-exchange format was also an important tool in the process. The experience of digital mapping is described from the point of view of a private, photogrammetric mapping company.
The further development of remote sensing applications depends on an enhanced dialogue between those who master the technique of remote sensing and the ultimate users. A correct balance between the technology push and the market pull is not always easy to strike in this area. Within the Commission of the European Communities, services are working together on the one hand, on implementation of policies related to agriculture, environment, assistance to developing countries, regional development and raw materials and, on the other hand, on JRC research to promote new applications of remote sensing. These concerted efforts have led to successful results which clearly establish the benefits derived from each observation from space, for certain sectors of socio-economic relevance.
Matrix decomposition techniques are used in order to obtain efficient structures for 2-D quadratic digital filters. The proposed structures consist of parallel branches which operate simultaneously on the input array. Each branch is formed by a 2-D FIR filter in cascade with a squaring operator, and all the partial results are summed up to obtain the output value. In the paper it is shown that, in particular, the lower-upper (LU) decomposition permits computational and hardware advantages.
