Quantification of quality parameters of inland and near shore waters by means of remote sensing has encountered varying degrees of success in spite of the high variability of the parameters under consideration and limitations of remote sensors themselves. This paper com- prehensively evaluates the quantification of four types of water quality parameters: inorganic sediment particles, phytoplankton pigments, coloured dissolved organic material and Secchi disk depth. It concentrates on quantification requirements, as well as the options in selecting the most appropriate sensor data for the purpose. Relevant factors, such as quantification imple- mentation and validation of the quantified results are also extensively discussed. This review reveals that the relationship between in situ samples and their corresponding remotely sensed data can be linear or nonlinear, but are nearly always site-specific. The quantification has been attempted from terrestrial satellite data largely for suspended sediments and chlorophyll con- centrations. The quantification has been implemented through integration of remotely sensed imagery data, in situ water samples and ancillary data in a geographic information system (GIS). The introduction of GIS makes the quantification feasible for more variables at an increasingly higher accuracy. Affected by the number and quality of in situ samples, accuracy of quantifica- tion has been reported in different ways and varies widely.

Quantification of shallow water quality parameters by means of remote sensing

Topographic mapping from SPOT imagery.

The use of Structure-from-Motion (SfM) and Multi-View-Stereo (MVS) approaches to build 3D models of structures belonging to the Cultural Heritage environment is becoming more widespread. Du...

Use of SfM-MVS approach to nadir and oblique images generated throught aerial cameras to build 2.5D map and 3D models in urban areas

The applicability of image calibration to like-values in mapping water quality parameters from multitemporal images is explored, Six sets of water samples were collected at satellite overpasses over Moreton Bay, Brisbane, Australia. Analysis of these samples reveals that waters in this shallow bay are mostly TSS-dominated, even though they are occasionally dominated by chlorophyll as well. Three of the images were calibrated to a reference image based on invariant targets. Predictive models constructed from the reference image were applied to estimating total suspended sediment (TSS) and Secchi depth from another image at a discrepancy of around 35 percent. Application of the predictive model for TSS concentration to another image acquired at a time of different water types resulted in a discrepancy of 152 percent. Therefore, image calibration to like-values could be used to reliably map certain water quality parameters from multitemporal TM images so long as the water type under study remains unchanged. This method is limited in that the mapped results could be rather inaccurate if the water type under study has changed considerably. Thus, the approach needs to be refined in shallow water from multitemporal satellite imagery.

Image calibration to like-values in mapping shallow water quality from multitemporal data

he usefulness of space shuttle Large Format Camera (LFC) photographs for urban land-use and land-cover mapping at 1:50,000 scale was evaluated using the Boston Metropolitan Area as the test site. Black-and-white panchromatic National High Altitude Photographs (NHAP), which are usually employed by Federal and State agencies for land-use and land-cover mapping, were also evaluated for the same test site so that a comparison could be made with LFC photographs. Visual interpretation of urban land-use and land-cover types at Level 111 as a detailed categorization of Level I1 of the uscs classification scheme was carried out for both sets of photographs. Ground-truth data were also obtained from a land-use and land-cover map of Boston produced by the Department of Forestry and Wildlife Management, University of Massachusetts at Amherst at 1:25,000 scale, to which the maps produced from LFC photographs and NHAP were compared. It was found that an overall accuracy of 65 percent was achieved for the map from LFC data and 70 percent for the map from NHAP data, thus demonstrating that LFC photography was comparable in performance to NHAP data as an urban land-use and land-cover mapping tool by virtue of its excellent geometric accuracy, favorable base-height ratio, and high spatial resolution. It was also noted that object-to-ground contrast and the distinctiveness of image element characteristics determined the success of discriminating complex urban land-use/ land-cover classes using LFC photographs, which resulted in high variations in accuracy among Level 111 categories. It was concluded that LFC photographs should best be employed to produce urban land-use and land-cover maps at the more generalized Level I1 categories at 1:50,000 scale.

Detailed urban land-use and land-cover mapping using large format camera photographs : an evaluation

Space borne image data at high spatial and radiometric resolution is becoming increasingly available. The Large Format Camera (LFC) photographs are of unmatched spatial resolution and thus of great interest for an ever increasing user community. This paper investigates into the point positioning and mapping capabilities of the LFC system. Point positioning accuracy is explored for planimetry and height with respect to strip triangulation and single stereomodel processing. Identification and interpretation of map features, and the map updating capabilities are analysed in relation to the map standards of a topographic map 1:100 000. Experiences with Digital Terrain Model generation and orthophoto production are reported.

E. Spiess

Papers

Point positioning and mapping with large format camera data