Showing posts with the label RS Analysis

Tutorial on Digital Image Processing Steps

Introduction to Digital Image Processing Digital Image Processing is the implementation of mathematical methods and algorithm on digital images for correcting, improving, analyzing and creating information. Nowadays remote sensing data are available digitally therefore process performed on these image also defined as digital image processing.  Image processing is combination of processes in which different techniques deployed for editing, manipulation of digital images using image processing software .  It is important to understand that the main aim of this processing is to extract information from satellite image , which are not readily available in satellite image, such as built up area, water body etc.   To process satellite image digitally, the remote sensing data (i.e. satellite images/aerial photographs) must be recorded and facilitate only in digital form.  Instead of digital satellite images , other requirements of image processing are computer system with appropriate

Digital Image Processing Tutorial- Satellite Image Interpretation Part-III

Image Interpretation Elements As discussed in last article about image interpretation and also defined image interpretation elements/keys. Elements/Keys are below- Figure-Use of Elements/Keys for Image Interpretation Size Shape Shadow Tone/Color Texture Pattern Height & depth Site Association Color Color is primary element and convenient to identify and recognize earth surface feature on multi band satellite image. Color images can be obtained by combination of three bands and two type of combinations can be prepared, first Natural Color composite (NCC) and the second one is False color composite (FCC). In both type of combination color may vary for the same feature, such as vegetation appears green in NCC whereas it will appear red in FCC. Figure- Color variation in FCC and NCC Tone It refers to the average brightness of an area or, in the case of color imagery, to the dominant color of the region. It depends on the nature of the surface

Digital Image Processing Tutorial-Satellite Image Interpretation Part-II

Image interpretation The main objective of image interpretation is to create information in the form of thematic maps. A thematic map can be prepared by categorizing all pixels of the image into classes or themes to generate map from the remote sensing data .  One can take different theme based on field of study, for example one can create Land use/land cover map based on mapping different categories such as water, forest, range land, urban etc. Mapping and quantification of surface water bodies / water resources. Geological map based on identification of landforms, rock types, folds, faults and fractures. Urban change detection maps using multi date remote sensing data . Below steps followed for Image Interpretation- Classification                Assign objects to classes                Detection, recognition, identification.                Interpreter confidence is ranked as possible , probable Measurement               Uses image scale to derive measure

Digital Image Processing Tutorial - Image Interpretation of Satellite Images

Principle of interpretation of aerial photographs and satellite images This is the part of image processing , in which images are processed and relevant information in the form of land use/land cover maps can be created.  Image interpretation is defined as the extracting quantitative and qualitative information using satellite image / aerial photographs by using field experience, direct recognition and inference. Remote sensing - image interpretation is a powerful tool because it gives: The aerial and regional perspective The three dimensional depth perspective in the form of DEM Knowledge beyond our human visual perception The ability to obtain a historical image record to document change through Mapping This topic/article has three important key words to discuss Aerial photographs and satellite image Principle Interpretation Aerial photographs and satellite image Aerial photographs/ satellite image are used as basic input for this procedure. These satellit

Digital Image Processing Tutorial- How to Re-project Satellite Images

Re-project Satellite Image This article Shared to understand projection and re-projection procedure and its importance in remote sensing images and database. Projected satellite images  means that images are projected and they have coordinate information as well as a defined projection model to define the shape of our earth. One of the best  example of projected raster and vector data,  which is used by  everyone now a days using through many online app or websites. In our daily life, we used to locate our self  to find the transportation route to our destination or shortest path to reach our selected location. This process, we used to do by using different maps based apps or websites. This correct shortest path or find route to destination only possible due to this projected database working behind in that app or website otherwise one will get distorted locations or route.   Projection Procedure Projection is very significant and important procedure in remote sensing and

Digital Image Processing Tutorial-Mosaic Satellite Image

In this article further important processes will be explained, which are required during digital image processing . For Example - After acquiring satellite images based on study area one may need more than one satellite image to cover study area for analysis. So to cover this study area one may need more than one satellite image and in this case similarity and uniformity for all satellite images become essential to achieve qualitative and quantitative accuracy in analysis. It is also to keep uniform contrast, brightness and enhancement level for satellite images for better interpretation and analysis. These above process can be performed using image processing software . Advantages of Mosaic Tool If any user have more than one satellite image for his study area than make a single image from all satellite image is necessary process for similar outcome. Mosaic all satellite image of study area to make a single satellite image through mosaic tool available in image processing s

Digital Image Processing Tutorial--Layer Stacking and Subset a Satellite Image

Satellite Image Processing Satellite image processing include various steps and processes to make image ready for interpretation and classification . These processes are important on each step of image processing such as geometric correction, radiometric correction, enhancement , classification etc. These processing methods are also depend on number of bands present in image as well as on spatial and temporal properties of satellite image . In this article some basic image processing tools are discussed using  Erdas Imagine. As data downloaded/purchased than there may be some basic operations need to perform for digital image processing . These tools may vary with data acquired, in general satellite data need to stack, subset, mosaic and re-project based on the project requirement and data availability. Layer Stacking: This process is primary process after acquiring satellite images as most of the satellite images are provided in different bands or layers , such as