Color-infrared Photography Research Articles

Remote Sensing of Macartney Rose in the Texas Coastal Prairie

Macartney rose (Rosa bracteata) is an evergreen shrub that often creates a range management problem in southeastern Texas. A study was conducted to determine the potential of using remote sensing technology to distinguishMacartney rose on the Texas Coastal Prairie. Field reflectance measurements showed that Macartney rose had higher near-infrared reflectance than associated plant species and mixtures of species in February and March. Macartney rose had a bright red image tonal response on color-infrared aerial photographs obtained in late winter. Computer analysis of a color-infrared photographic transparency showed that Macartney rose populations could be quantified. An accuracy assessment performed on the classified image showed that both the user's accuracy and producer's accuracy for Macartney rose were 100%.

Interpretation of mopane woodlands using air photos with implications on satellite image classification

Delineation of stands of Colophospermum mopane is carried out on aerial photographs for the area around Palapye, Botswana. The purpose of this study was to evaluate aerial photos as ground truth material for satellite image classification, and to assess the quality of an existing vegetation map around the study area. Colophospermum mopane can be accurately mapped using colour infrared (CIR) photographs. The study shows that CIR photography can be used for accurately mapping the distribution of mopane. This material can therefore, be used as a reliable tool for ground truthing vegetation classification of satellite images, as well as for monitoring the distribution of the species. The only pre-existing vegetation map over the study area is checked against a visually interpreted map for consistency of the level of detail. A close-up view of pictures of scanned CIR air photos are used to study tree shadow characteristics of Savannah vegetation. Results from this investigation are used to explain the concept of the darkening effect, prevalent on Savannah environments. A model is presented to show the effect of tree shadows on brightness values and on NDVI measured by satellites.

Reflectance Characteristics and Remote Sensing of a Riparian Zone in South Texas

This paper presents data on utilizing remote sensing technology for characterizing a riparian zone in southern Texas. Radiometric ground reflectance measurements, color-infrared aerial photography, and computer image processing techniques were conducted for this study. Reflectance measurements were made on 8 dominant vegetation types, soil, and water. Spectral measurements were made in the visible green (0.52-0.60 μm), visible red (0.63-0.69 μm), and near-infrared (0.76-0.90 μm) wavelengths. Reflectance values differed significantly (P = 0.05) among the vegetation, soil, and water parameters at all 3 wavelengths. Differences in reflectance among the vegetation cover types were attributed to variable foliage coloration and vegetative density. A color-infrared photograph of the study area showed that many of the ecological surface types could be readily distinguished. An unsupervised computer classification of the photograph identified 8 ground classes. An accuracy assessment performed on the classification showed an overall accuracy of 88%.

Low-cost ground-based digital infra-red photography

The paper describes how many types of inexpensive digital camera can be used to take monochrome and false colour infra-red photographs. The method avoids many of the limitations of infra-red sensitive film and produces excellent results rapidly and at low cost.

Normalization of bi-directional effects in aerial CIR photographs to improve classification accuracy of boreal and subarctic vegetation for pollen-landscape calibration

Bi-directional effects were quantified and normalized in colour infrared (CIR) aerial images in order to produce high accuracy, high-resolution vegetation maps for the needs of pollen-landscape calibration. Three areas in northern Finland with different vegetation types were studied. The brightness variations of the most typical land cover type of each study site were quantified by examining the change of mean DN values of the reference sample areas on three separated wavelength bands in the overlapping images. Correlations between DN values and the scattering angles of reference sample areas were taken into account while normalizing bi-directional effects. The normalization was validated by classifying the images both before and after the normalization and assessing the classification accuracy. The accuracy increased on every study site after normalization. The highest increase was achieved in areas of uniform mountain birch forest. Increase was considerably lower on areas of fragmented vegetation. The resulting land cover classifications were used as landscape information in pollen-landscape calibration.

Challenge of Infrared Kite Aerial Photography

Kite aerial photography (KAP) involves the use of large kites to lift compact camera systems for capturing images of ground features. Our goal has been to develop equipment and techniques for infrared kite aerial photography. Attempting to conduct infrared photography from kites has proven to be a considerable challenge for several reasons. Among the most important limitations are those inherent in infrared film and conventional cameras. Infrared film has no ISO speed rating, and camera light meters do not measure infrared energy in the scene. Furthermore, KAP equipment should be relatively compact, rugged, light weight, and inexpensive.We have designed, built, and field tested two KAP rigs based on the Canon EOS RebelX camera, which is a 35-mm, full-featured, SLR camera. Our first rig is a dual-camera setup, in which the cameras take simultaneous color-visible and color-infrared photographs. This rig has radio control of the camera shutters. Camera tilt and pan positions are set manually prior to each flight. The second rig is for a single camera (color-infrared only); the rig has full radio control for pan, tilt, and shutter. The dual-camera rig weighs 1.5 kg, and the single-camera rig is just over 1 kg. Based on considerable field testing, we have determined appropriate manual light settings under full-sun conditions–1/250 shutter speed and f-9.5 aperture. Our preliminary results suggest that infrared KAP may be valuable for detailed investigations of vegetation, soils, and other environmental features.

Evaluation of color-infrared photography for distinguishing annual changes in riparian forest vegetation of the lower Rio Grande in Texas

The Rio Grande is significant for its role in the history of the USA and Mexico and is the second longest river system in the United States. The riparian vegetation of the Rio Grande in Texas is poorly known. We employed aerial color-infrared (CIR) photography to investigate patterns of distribution, species composition, and annual changes in riparian vegetation at two sites in the lower Rio Grande Valley. The line-intercept technique of vegetation analysis was used to provide ground truth and to assist in the correlation of imagery and vegetation discrimination, distribution, and abundance. Celtis laevigata (sugar hackberry) was the dominant tree species at Bentsen-Rio Grande Valley State Park (BRG) near Mission, Texas, and Prosopis glandulosa (mesquite) and Parkinsonia aculeata (retama) were the dominant species at Salineño (SAL) near the outflow of the Rio Grande from Falcon Dam. Celtis pallida (granjeno) was the dominant shrub species at both sites, and the introduced grasses, Panicum maximum (Guineagrass) and Cenchrus ciliaris (buffelgrass) were the dominants in the ground layer at BRG and SAL, respectively. Aerial CIR photography appears to be useful in discriminating certain tree species. However, due to tonal similarities, it is difficult to identify each of the species in the canopy. An important value of the technique is the monitoring of senescence and death of trees in the riparian zone between successive years.

Using Airborne Digital Imagery for Detecting Oak Wilt Disease.

Color-infrared (CIR) digital imagery was evaluated as a remote sensing tool for detecting oak wilt disease in live oak (Quercus fusiformis). Aerial CIR digital imagery and CIR photography were obtained concurrently of a live oak forested area in south-central Texas affected by oak wilt. Dead, diseased, and healthy live oak trees could generally be delineated as well in the digital imagery as in the CIR photography. Light reflectance measurements obtained in the field showed that dead, diseased, and healthy trees had different visible and near-infrared reflectance values.

Automatic determination of imperviousness in urban areas from digital orthophotos

Determination of impervious areas in urban regions is the most labour-intensive part of data acquisition for rainfall-runoff modelling in urban hydrology. This paper presents an automatic determination method of imperviousness from aerial photographs. The colour, CIR (colour infrared) aerial photographs and orthophotos used have a ground resolution of 25 to 75 centimetres. A maximum likelihood classification algorithm was applied to assign each pixel to a surface category. Classification results were then overlaid with the subcatchments to determine the imperviousness of each subcatchment. Classification and overlay were carried out with the raster-based GIS IDRISI. The method was tested on various catcbment areas, and the results compared with data obtained from manually digitised surfaces. Accuracy of the estimated imperviousness for the entire catchment areas was within 10%. The deviations for individual subcatchments were much higher. Equivalent results were obtained for colour and CIR photographs. A combination of both spectral ranges resulted only in a slight improvement. Consequently, this does not justify the additional costs of the second image. The developed method is an interesting alternative for use on large catchment areas where manual digitisation is very time-consuming and, thus, expensive.

The characterization of natural vegetation using first-order and texture measurements in digitized, colour-infrared photography

Abstract A video-digitized, aerial colour-infrared photograph of a species-rich mire site was analysed to explore its information content with respect to ecologically important site characteristics, viz., species richness and structural diversity. First-order (mean and standard deviation) and texture measures (semivariance, angular second moment and inverse difference moment) were calculated for image windows representing 2 by 2 m vegetation quadrats. For each quadrat the number of herbaceous species (SPPH), the cumulative cover of herbaceous species (COVH) and moss (COVM) and a structure-diversity index (DIVC) were derived from the complete recordings of species composition and species cover per quadrat. The diversity index is made up of structure classes based on species morphology and maximum height. Stepwise regression was used for the explanation of the variance in these statistics observed between the quadrats. The additional value of the texture measures was assessed relative to a base model containing red and near-infrared only. COVH and DIVC appeared to be sufficient as descriptors of species richness and structural diversity; 30 and 60 per cent of the variance respectively is explained by the base model. The addition of semivariance resulted in an improved model only for SPPH and COVH. Biological and physical arguments are provided for explaining the behaviour of each statistic.

Aerial Photography and Videography for Detecting and Mapping Dicamba Injury Patterns

Field trials were conducted to compare on-site visual evaluations with color-infrared photography (CIR), and near-infrared (NIR) videography (video) and hand-held radiometry (HHR) for detecting and mapping dicamba injury in cotton. CIR, video, and HHR detected 48%, 42% and 36%, respectively, of the injured crop area as defined by visual evaluation (injury ratings >0 on a scale of 0 to 9). The remote techniques were unable to differentiate crop injury that did not involve the entire plant canopy. Reflectance measurements in the visible red (R) (630–690 nm) and NIR (760–900 nm) wavelengths were taken and used in herbicide dosage prediction equations. Predicted herbicide dosages were significantly, positively correlated (P≤0.01) with physical measures of herbicide present. These studies suggest that remote detection and mapping of moderate and severe herbicide injury is possible. Further, NIR videography, with near-real-time capability and low cost may be the system of choice for this type of application.

The Identification of Blue Pigments in Early Sienese Paintings by Color Infrared Photography

The Identification of Blue Pigments in Early Sienese Paintings by Color Infrared Photography

The Identification of Blue Pigments in Early Sienese Paintings by Color Infrared Photography

This article presents the results from a color infrared photographic study of the occurrence of ultramarine and azurite in a group of 13th- and 14th-century Sienese panel paintings. Color infrared ...

Measurements of Citrus Tree Health with a Scanning Densitometer from Aerial Color Infrared Photographs

Aerial color infrared (CIR) photographs of citrus trees were analyzed with a scanning densitometer (SCND) to obtain spectral curves for comparison with arbitrarily assigned visual grades (VG). Spectral curves derived from healthy and declining tree rows had one peak at 500-520 nm and another between 600 and 620 nm. Comparisons between VGs and integrals (peaks I 1 and I 2) showed little difference between them, nor between VGs and percentage of transmittance values (T 1 and T 2). Spectral ratios of the integrals (SRG) and spectral transmittance (SRT) separated the VGs into three different groups, suggesting that a reduction from five to three VGs would make densitometric measurements more realistic

THE STUDY AND MAPPING OF HUMAN IMPACTS ON NATURE IN DIFFERENT REGIONS OF THE USSR USING SPACE IMAGERY

The authors present the results of experiments in the use of remote sensing imagery for construction of maps depicting human modification of nature. Four diverse areas within the USSR were selected as mapping sites, providing a broad range of environmental and land-use characteristics for investigation. Human impacts were most effectively mapped for two desert sites. The authors recommend combining satellite imagery with terrestrial spectrometric observations or color-infrared photography in investigations of environmental change in steppeland and forested territory. Translated from: Vestnik Moskovskogo Universiteta, geografiya, 1984, No. 6, pp. 11-18.

Natural-color and color-infrared photography for the identification of forest-stand density, height, and species composition

Natural-color and color-infrared aerial photography at scales of 1:30 000, 1:50 000, and 1:70 000 were evaluated for the interpretation of forest-stand density, height, and species class, for test areas in the boreal and foothills regions of Alberta. Accuracy was assessed by comparing photo interpreter identification to field measurements. When averaged over all scales, color film types did not differ in accuracy. Scale affected identification accuracy for density and species class. The 1:70 000 scale was most accurate for estimating density and least accurate for species class. Scale did not affect identification accuracy for 6-m height classes. Interpreter inventory experience and color-discrimination ability both affected accuracy for species class, but not density or height. Standard 1:15 000 scale black and white photography was not significantly more accurate than any of the other film–scale combinations for identification of density, height, or species class.

Multispectral Remote Sensing of Saline Seeps

An aircraft experiment was conducted in early summer of 1981 to determine the feasibility of optical and microwave remote sensing techniques for the detection of fully developed and incipient saline seeps in South Dakota and Montana. The NASA C-130 earth resources aircraft was used to acquire L-band and C-band scatterometer data (backscattering coefficient profiles), radiometer data (brightness temperature profiles), and color-infrared photography; additional passive microwave data and thermal images were acquired by the L- band radiometer on the Beechcraft D-18 aircraft operated by South Dakota State University. Intensive soil moisture and salinity data were collected on a uniform 20-m grid spacing and at several depths for the 600 × 600 m South Dakota site. The two Montana sites were over-flown with flight lines several kilometers in length, and ground truth information was obtained by identifying known geological and geohydrological units with varying soil salinities on a regional basis. The C-130 radiometers (both L- and C-bands) were effective in detecting wet soil areas including fully developed seeps; however, incipient seeps were not accurately detected by the radiometers. The D-18 L-band radiometer data did not appear to be sensitive to soil wetness. The C-130 scatterometer data profiles, although showing some sensitivity to soil moisture, were greatly influenced by surface roughness and appear to be ineffective in accurately delineating either fully developed or incipient seeps. Thermal-IR scanner data acquired by the D-18 aircraft did not appear to provide a reliable means for identifying potential seeps.

A system for quantitative determination of species and vitalities of urban trees on color-infrared photographs

Aerial color-infrared photographs of two Swiss cities (Bern and Lausanne) were taken to evaluate the potential use of automatic image analysis for the discrimination of urban tree species and their different vitalities. A TV-based hardware system under full software control measured five different functions at each of the 63 possible intensity levels at red (600 nm), green (550 nm), blue (470 nm), and white illumination. Eighty-three parameters per tree were derived from the corresponding intensity distributions describing tone and texture. Classification by supervised learning was carried out using stepwise discriminant analysis. The overall classification error for the discrimination of four deciduous tree species (horse chestnut, Norway maple, large-leaved lime, and London plane) was 4.9%. A higher error rate (6.2%) was found for the discrimination of five classes, namely healthy trees of the above mentioned four species and damaged horse chestnut trees. The practicability of the proposed system is discussed.

Use of Color Infra-Red Photography in the Delineation of Wetlands Vegetation in a Texas Gulf Coast Watershed

SUMMARYColor infra-red photography at a scale of 1:12,000 flown in September 1975 was used as an aid in mapping wetlands vegetation in the Little Robbins Slough watershed of coastal Texas. This mapping was to serve as a baseline for long-term monitoring of subtle changes in the wetlands system. A Bausch & Lomb Model ZT4 Transfer Scope was used to facilitate mapping at a scale of 1:6,000. Vegetation types were assigned on the basis of life-form differences and subtypes on the basis of compositional differences. Infra-red colors and textures, together with life-form information and ground reconnaissance, were used to identify vegetation types, subtypes and species. Signatures were obtained for 22 species or species combinations. Assignment of several sets of color/texture combinations was required for plant species occurring under a variety of substrate conditions. There was a general increase in complexity of vegetation from brackish to fresh wetlands. The minimum sized area mapped was 0.04 ha and the mini...

AERIAL PHOTOGRAPHY FOR DETECTION AND ASSESSMENT OF GRASSHOPPER (ORTHOPTERA: ACRIDIDAE) DAMAGE TO SMALL GRAIN CROPS IN SASKATCHEWAN

AbstractAerial colour infra-red photographs were used to detect grasshopper damage to cereal grains, determine extent of damage, estimate crop yield, and identify crops. The detection and identification of grasshopper damage was facilitated by the development of a dichotomous key which differentiates grasshopper damage from other crop anomalies. Crop types and yield were determined from correlations between the optical density of the photographs and the biomass of standing crops.Cost of an aerial survey was estimated at $0.02 per hectare as compared with ground survey cost of $0.20 per hectare. Information provided by an aerial survey of damage has the potential to assist grain growers, extension personnel, and researchers in evaluating the influence of grasshoppers on grain production