Small-format Aerial Photography Research Articles

Some tests of film types for remote sensing of purple loosestrife,Lythrum salicaria, at low densities

Purple loosestrife,Lythrum salicaria, is an exotic plant that has proven to be extremely competitive with native wetland and riparian zone species. Current control measures are limited and most effective when infestations are detected at an early stage. The goal of this project was to provide a detection tool (remote sensing) for relatively small loosestrife infestations. Small format (35 mm) aerial photography was acquired over seven sites in central Washington during the peak bloom period ofL. salicaria. The sites were selected to provide a variety of typical background plants and a range of infestation sizes, from a few isolated individuals to large, monospecific stands. All sites were photographed at approximately 1∶5000 (large) and 1∶12,000 (small) scale with Fuji Velvia 50 and Kodak Kodachrome 64 color transparency films. Sixteen sample slides were ranked by 46 interpreters according to the ease of finding loosestrife flowers. As expected, the interpreters ranked massive loosestrife stands as the most easy to identify. However, a large scale image of single loosestrife flowers was ranked almost as easy to interpret as the high altitude imagery of massive stands. Loosestrife was most difficult to detect on imagery from sites with few loosestrife plants or with large amounts of dead plant material below the flower heads. Differences in film type were significant, ranking in order of decreasing ease of interpretation: Fuji Kodachrome. Remote sensing using small format aerial photography can be successfully applied to discriminate flowering loosestrife plants from other background wetland vegetation. Color slide transparencies taken at 1∶5000 or larger scale can show flowers in sufficient detail for detection and mapping of isolated plants. Screening of interpreters can enhance the probability of proper interpretation and detection. Fuji Velvia 50 or other films that provide greater saturation of green colors can offer an advantage in detection.

Surveying a Waste Site with 35-mm Oblique Aerial Photography: Monoplotting with a Digitizing Tablet

Hand-held, small-format (35-mm) aerial photography can provide reliable measurements for geographic information system (GIS) data collection. This article presents a waste-site investigation in which a digital monoplotter was used to capture measurements from enlarged 35-mm oblique photography. Smallformat overlapping photography was used to create a digital elevation model, which supplied elevation data for digital monoplotting. Point locations for installing monitoring instruments were plotted on a single 35-mm photograph (1:5,187 scale) and subsequently were located in the field with 43-cm accuracy. Results suggest the low-cost method is suited for waste-site investigations and GIS data capture.

Updating urban maps with analytically rectified Small Format Aerial Photographs

Small Format Aerial Photography (SFAP) is a new emerging art of acquiring photogrammetric data with metric and non-metric cameras. SFAP with format size normally less than 55×55 mm, possesses the potential of both compiling new maps and updating existing planimetric maps of small areas. Organisations dealing with urban and other large-scale mapping, may be benefited greatly by the use of such data. In the present study, investigations are carried out to update an urban map on scale 1∶10,000 using analytically rectified SFAP from non-metric camera. Results are encouraging and presented in this paper.

Remote Sensing and Proximal Sensing in Ecological Monitoring

The author discusses the advantages and disadvantages of satellite imagery and large &small format aerial photography. The author has developed a facility named 'Vihangam Alok' - a specifically modified aircraft with a camera and processing laboratory for collection and analysis of data.

Urban environmental surveys: Information gathering, low cost aerial photography and town management

In the less developed countries of the world today the population of the towns and cities is increasing at a rate much faster than the urban management system can provide the infrastructure. The great majority of these towns do not have large-scale town maps with which to plan and programme such work, nor are there any up-to-date maps which can be used for the ‘cadastre’ for increasing revenue from the land and property ownership. Small format aerial photography and personal computer mapping technology can now provide low cost, and adequate, large-scale town maps, along with a town data base, as an immediate aid to the urban management problem in those countries.

Evaluating small-format photogrammetry for forest and wildlife surveys: Euclidean vs. fractal geometry

The recent interest in small-format (35-mm and 70-mm) aerial photography for photogrammetric purposes has brought criticism of the small camera's geometric instability and limited accuracy. Metric accuracy of any camera is based upon Euclidean geometry; but the geometry of fractals must also be examined to determine overall precision of photo-measurements. In measuring fragmented shapes (typically found in nature), the influence of fractal geometry could dwarf the influence of Euclidean geometry, and mitigate the basic criticism of small-format aerial surveys.

CONSIDERATIONS OF SPECIFICATIONS FOR SMALL FORMAT AERIAL PHOTOGRAPHY

AbstractFollowing the success of the symposium held by the Photogrammetric Society on 31st March, 1987, a second one‐day symposium was convened to give further support to the rapidly growing interest in the development of small format photography for aerial survey. This was held at Burlington House, London on 1st November, 1988. Over 70 people attended. Six of the papers are reproduced here, dealing with a range of topics including specifications for and navigation of small format aerial photography, the creation of digital terrain models from 35 mm photography, wildlife surveys in the Arctic and survey photography from model aircraft and tethered balloons.

Benefits of small-format aerial photography

In this article the benefits of using small-format cameras (35 mm) for aerial photography are presented, and new films, camera platforms, including microlight aircraft, and photogrammetric instruments for collecting primary data off the aerial photographs, are discussed.

The geomorphic impact of the catastrophic October 1984 flood on the planform of Squamish River, southwestern British Columbia

Small-format aerial photography of Squamish River just prior to and immediately following the October 1984 flood of record forms the basis of a quantitative evaluation of floodplain erosion and construction during this extreme event. Channel changes in 1984 are compared with those determined from sequential aerial photography at various other times since 1947 and associated with less extreme flooding.Depending on the type of river planform, the degree of channel change during the 1984 flood varied from a relatively minor response to a major reorganization of the channel. Despite its large size, the 1984 flood accomplished little more floodplain modification in the meandering and transitional semibraided reaches than had previous smaller floods of similar duration. In general, greater erosion was accomplished here by relatively small but longer duration flood events. In contrast, in the braided reach the 1984 flood caused floodplain erosion and major reorganization of the channel to an extent previously unrecorded, apparently here exceeding a threshold for channel stability. For all reaches, variation in floodplain erosion among sites was greater than at-a-site variation in erosion related to flood history.

Student projects at Queensland Centre for surveying and mapping studies

Projects by students using terrestrial and small format aerial photography satisfy educational and community needs by combining photogrammetric techniques and state of the art technology.

A Method of Hazard-Rating White Spruce Plantations For Yellowheaded Spruce Sawfly Defoliation

Abstract A hazard-rating model for defoliation by the yellowheaded spruce sawfly was developed and validated using 25 white spruce plantations in north central Minnesota. The dependent variable was degree of defoliation, and the independent variables, as measured from small-format aerial photographs, were steepness and slope aspect. The site characteristics and defoliation were correlated using a maximum likelihood logistic regression. The final model determined that steep, south-facing slopes had the highest probability of sawfly-caused defoliation. Identification of high-hazard sites should be a major component of a management plan for this pest. North. J. Appl. For. 3:104-105, Sept. 1986.

Lake Level Effects as Measured from Aerial Photos

Rising Lake Michigan water levels were found to negatively influence the amount of wetlands and beaches in the Straits of Mackinac area of Lack Michigan. The effects of long-term fluctuation in water levels were determined from measurements of wetlands and beaches on seven sets of historical aerial photographs (1938-1980). Analysis of aerial photographs demonstrated a 380 acre (154 ha) difference in total wetland and beach areas at the highest lake level sampled. as compared to the total at the lowest lake level sampled, or a range of 4 ft (1.2 m). A linear model between total wetland and beach areas and water levels (R²=0.93) indicated an increase of one foot (0.3 m) would result in a decrease of 80 acres (32 ha) or 18% of the 439 acres (178 ha) of wetlands and beaches in the study area. This methodlogy, which includes measurements from historical aerial photographs, acquisition of small format aerial photographs, and determination of local hydrological conditions, was useful for quantifying change in these lacustrine wetlands.

Plantation white spruce mortality: estimates based on aerial photography and analysis using a life-table format

White spruce, Piceaglauca (Moench) Voss, mortality was estimated in two 142-ha, 11- and 12-year-old plantations in north central Minnesota, using small-format color aerial photography at a scale of 1:9600 and groundplots. A double sample with regression sampling method determined mortality of trees 5 years after planting to be 3.9 ± 0.33%. Life-table analysis showed 20.7% loss during the first age interval, 0–4 years after planting. The yellow-headed spruce sawfly, Pikonemaalaskensis (Rohwer), was responsible for 65% of the mortality in the last two age intervals. Differential mortality and growth of white spruce was observed between plantations. Site preparation is suggested as a possible cause of these differences.

Simple and cheap do-it-yourself technique

Abstract Throughout the developing world there is a continuous movement of families from rural areas to towns and cities. Trying to record and map the location of all these newcomers is a massive surveying job, and, at best, it is many months before a large-scale map of a district is available, by which time it will already be out of date. Quick and economical means of accurately mapping districts where these rapid changes are taking place is now possible by using light aircraft and small format (35 mm or 70 mm) cameras. The first issue of Cities detailed the aerial photography campaign employed in Managua in the 1970s.1 We now follow this up with two articles contributed by the International Institute for Aerial Survey and Earth Sciences. In the first, Dr Hofstee provides an urban planners guide to small format aerial photography. In the second, J. Buwalda describes an application of the technique to a shanty town in Colombo, Sri Lanka.2

Small Format Aerial Photography from Microlight Platforms

AbstractConventional survey aircraft, with their sophisticated camera and navigation systems, are mainly designed to cover the photogrammetric requirements of line mapping. But for less exacting cover, such as urban or rural surveys, map intensification, crop inspection, estate management, forest inventories and multispectral photography, there are urgent reasons for seeking more economic methods of gaining the primary data. To this end the authors have initiated trials with commercially available microlight aircraft employing small format (35 mm and 70 mm) cameras in order to investigate the various flying skills, materials and strategies that will lead to the optimum economic system for developing countries.

Environmental application of aerial reconnaissance to search for open dumps

Three approaches to using aerial photography are evaluated for searching for open dumps in the state of Indiana. Photography with hand-held cameras from a small airplane proved more effective and flexible than either photo-interpretation of existing air photos or subcontracting to a federal agency for new aerial photography. The rationale for our choice of aerial reconnaissance, other uses of low-level aerial surveillance, the utility of small-format camera aerial photography for environmental analysis, and methods used for locating open dumps are discussed.

Assessing spruce budworm damage with small-format aerial photographs

Methods of evaluating forest damage are designed to provide information for detection, control, and preventative management. In this study the use of small-format aerial photographs to assess spruce budworm, Choristoneurafumiferana (Clemens), damage was evaluated. A procedure was developed to identify spruce–fir stand vulnerability and establish inventory data for silvicultural management considerations. Large-scale (1:4800) 35-mm color positives of eight spruce–fir stands were obtained in July and August 1979. Defoliation intensity and tree mortality of host species were the parameters used to assess damage severity. Individual stands were assigned separate damage rating values based on aerial and ground survey evaluations of defoliation and mortality. Comparison of aerial and ground damage severity ratings was accomplished with a contingency table. Results show photointerpretation of forest damage condition matched ground inspection in seven of eight stands surveyed.

SMALL FORMAT, HAND HELD HELICOPTER BASED PHOTOGRAPHY FOR MONITORING INDUSTRIAL WATER EFFLUENT PLUMES

As a component of an environmental design study, the geometry and dimensions of the water effluent plume from the Stelco Steel making facility at Nanticoke have been mapped for six cases with different dispersion characteristics. Small format aerial photography is used to provide cost effective and accurate information on the dispersion confirgurations. Interpretation of this imagery is verified using water quality data collected during ground information missions co-ordinated with three of the aerial photography flights. The maps provide an invaluable addition to idealized model predictions by illustrating the plume behaviour that is peculiar to that particular physical setting.

Place of Small-Format Aerial Photography in Resource Surveys

Abstract With continuing escalation of field verification costs in renewable resource surveys, users of conventional aerial survey techniques are experiencing difficulties in maintaining cost-effectiveness within existing budget constraints. Judicious use of small-format (35-mm or 70-mm) aerial photography can often reduce time and costs of field verification without sacrificing quantity or quality in the data gathered. Examples of its use either as a supplement to conventional large-format photography or as the primary data base source are presented.

A lightweight illuminated device for viewing small format aerial photographs in the field

Summary The paper describes a simple, cheap, lightweight device which can conveniently be used for stereoscopic examination of small format transparencies in the field.