The choice of using the InSAR system for systematic mapping became from the need to generate more accurate geographical information, especially in dense forested areas, usually impenetrable. The OrbiSAR-1 was designed for this purpose. The system generates high-precision altimetry and planimetric maps through the X and P radar bands.
Using the X band is possible to generate digital surface models with exceptional accuracy and resolution that can reach up to 15cm in height and 25cm in spatial resolution. Including the P band, it also became possible to generate digital terrain models with greater accuracy because the ground under the trees canopy can be mapped, which considerably reduces the margin of error in the projects in which the knowledge of the topography with high precision is important. Furthermore, by being able to operate the radar at night and any weather, the data collection is performed in a limited time.
P and X bands
In principle, the Digital Terrain Model (DTM) could be generated by manual editing of the Digital Surface Model (DSM), using external information about the vegetation height. However, in this way, the result could include some errors, thus not meeting the accuracy requirements defined by the customer. To obtain the DTM with the required precision it´s necessary to use lower SAR frequency as P band.
The image below illustrates the X and P bands signals. The X-band waves are reflected and scattered through the treetops, while the P band penetrate the foliage and is reflected by the ground and the dense trunks, allowing the soil mapping under the vegetation.
The InSAR mapping technology allows BRADAR to produce different geographical information products quickly and accurately in order to meet the financial and technological goals specified by customers. This mapping system obtains better results than those obtained by other technologies for the following reasons:
- The data acquisition is independent of atmospheric conditions, allowing the short delivery of results, which is critical in case of urgent and emergency services. This flexibility in data acquisition enables compliance with deadlines for large projects, in which the sum of small end delays normally results in huge losses for the sheer size of these types of projects;
- The utilization of two frequencies simultaneously (X and P bands), providing both a measure of the height of the treetops as the soil under the vegetation. This allows the acquisition of images with and without vegetation coverage, revealing, in detail, surfaces unimagined and unknown water streams, illegal constructions, among other details;
- The simultaneously generation of the orthoimage of the observed area, which allows to obtain the low cost, high image quality and definition;
- The simultaneously generation of the Ortho-Rectified images, Digital Elevation Models, Digital Surface Models, Digital Terrain Models and derived products;
- Offers the only "one-stop-shop" solution for data acquisition, satisfying the needs and requirements of many critical applications requested by the remote sensing community.