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Posts Tagged ‘radar’

International Year of the Forests

Tuesday, January 25th, 2011

I once heard, ‘In order to have a healthy planet, we need to have healthy forests’. Deforestation has been a global issue for decades. In the 1800’s and 1900’s Europe, Russia, North Africa, and the Middle East had a vast amount of deforestation, but within the past decade theses regions have stabilized and re-growth is now beginning to occur. Today the majority of deforestation has and continues to occur in the taiga and tropical regions where the vast amount of our world’s forest lives. To raise awareness on sustainable management, development, and conservation of all types of forests, the United Nations declared 2011 the International Year of the Forests.

So what needs to be done to help assess and manage our global forests and what tools do we need to get started?

Firstly, we need to have accurate, up-to-date maps of our forests. Forested areas cover roughly 30% of the world’s surface, that’s about 40 million km². The forested areas are not spread evenly throughout the world, nor is it located within the same climatic regions. With a high percentage begin spread among taiga regions (North America and Russia) and tropical regions (South America and Southeast Asia) that have a large difference in climate and environment. Mapping these regions can be extremely difficult due to rugged terrain, extreme climate and weather conditions, consistent cloud cover, and triple canopy forest. As we all know, Fugro’s GeoSAR (Dual Band IFSAR mapping system) is known for resolving these mapping challenges as well as being best suited for large are mapping.

GeoSAR’s unique technology supports the collection, analysis, assessment, and management of forests and carbon estimation on a country-wide basis. With it’s foliage penetrating technology (P-band), GeoSAR is unique in it’s ability to derive detailed accurate terrain data in the thickest forests and densest jungles. The difference between the X-band and P-band data provides important information that is used to develop value-added data sets such as land use/land cover and biomass estimates. Combined with ground truth data and satellite monitoring, this information is found to be extremely valuable for the assessment and management of our global forest.

GeoSAR not only provides the technology necessary for accurately mapping these difficult environments but also can provide value- added products found necessary for forest assessment and management when combined with satellite imagery that provide essential monitoring capabilities. Below you will find an example of biomass estimation collected over a tropical region generated from GeoSAR data. Do your part in spreading the awareness for the International Year of the Forests, and please remember ‘In order to have a healthy plant, we need to have healthy forest’. Please feel free to leave a comment or request further information!

Biomass Estimation. The difference between GeoSAR's X-band and P-band data is used to calculate biomass estimations. Higher levels are shown with brighter colors.

Resolution

Monday, September 13th, 2010

Our previous post focused on GeoSAR’s capabilities for producing data with exceptional precision and accuracy. As a continuation, we’re focusing this week on yet another extremely important data characteristic in the remote sensing and mapping community — resolution. For the remote sensing community, resolution is an all too familiar and important aspect that defines how the end product is delivered to the customer.

GeoSAR is truly a one-of-a-kind mapping system because it is the only existing dual-sided, single-pass interferometric IFSAR system that simultaneously delivers X-band and P-band data. However, we often forget that radar technology, in itself, is quite remarkable in its ability to see through clouds and operate at night. GeoSAR takes radar technology one giant leap further with the addition of P-band. Unlike other IFSAR systems, GeoSAR’s P-band penetrates foliage and records returns from the bare-earth, even in extremely dry terrain. P-band also penetrates below the ground surface. Such conditions make mapping virtually impossible for most optical sensors, but GeoSAR was specifically designed to handle mapping’s most difficult challenges, all while maintaining the same resolution, regardless of the flight altitude. So how does IFSAR maintain imagery resolution with increased flying height? GeoSAR’s DbIFSAR image resolution is uniquely governed by the bandwidth of the transmitted signal.

Imaging radar has two principal directions:
1) The along-track direction oriented to the flight path of the aircraft, and
2) The slant-range distance from the radar to the ground, which is oriented perpendicular to the flight path.

Resolution obtained from the along-track direction is determined by Pulse Repetition Frequency (PRF), which is the number of times the radar “flashes” per second (per antenna). For example, the PRF for GeoSAR is approximately 500 Hz, so this direction is referred to as “slow-time.” The PRF actually varies with the speed of the aircraft in order to maintain consistent ground spacing between radar pulses. The ground speed of the GeoSAR aircraft is typically 225 m/s or 440 kts, so the data’s along-track resolution equals approximately 0.45 m.

Resolution obtained from the slant-range direction corresponds with the speed of light (300,000,000 m/s), so this direction is understandably referred to as “fast-time”. Since GeoSAR uses a bandwidth of 160 MHz, the inherent resolution in the range direction is approximately 300/2*160 = 0.90 m.

If you would like to learn more about GeoSAR’s precision, accuracy, and resolution, please leave a comment or send an email.

GeoSAR Graces the Cover of PE&RS

Tuesday, July 13th, 2010

GeoSAR will be gracing the cover of PE&RS this month which will be distributed at the ESRI International User Conference July 12th- 16th in San Diego, CA. Be sure to pick up your copy, view the cover, and read the feature article “Topographic Mapping Using IFSAR Data in a 3D Desktop GIS Environment” written by: L.G. (Jake) Jenkins and Larry Lund.

blog

The cover image represents a Digital Elevation Model generated from GeoSAR’s P-band radar overlaid with X and P-band orthorectified images, all in the ChromaDepth® color scheme. The orthorectified images were filtered to increase homogeneity, reduce speckling and remove artifacts. Waterways were flattened and rendered monotonic. The final images were composed into the scene using ESRI®’s ArcGIS software using a custom color pallet that allows the cooler colors to recede and warmer colors to advance on the eye when viewed using the ChromaDepth® 3-D glasses.

GeoSAR’s X and P-band orthorectified images are arranged split screen to highlight features such as terrain, agricultural fields and mangroves. P-band is located in the upper left as the X-band is located in the lower right. P-band highlights features associated with human settlements such as agricultural fields, irrigation channels, roadways and buildings, even those that may be hidden below the vegetation, whereas the mangroves appear brighter in the X-band imagery because they scatter more of the radar energy back.

GeoSAR is the world’s only dual-band, single-pass airborne interferometric SAR system. Penetrating clouds and foliage, GeoSAR simultaneously maps surface features (using x-band) and near bare-earth elevation (using P-band), making it particularly well suited for equatorial mapping.

Ground Control

Monday, June 21st, 2010

After receiving a significant amount of response for our metadata blog, we decided to discuss one of the most important aspects of any mapping project, ground control. Ground control refers to pre-marked or photo identifiable points on the Earth’s surface with known positions that is used either to process and rectify the raw geospatial data or to verify the accuracy of the final mapping products. Ground control networks are usually field surveyed in order to determine accurately their positions. However, other sources of accurate ground points can be used to verify and validate the accuracy of geospatial data products. Airborne LiDAR is excellent example of such sources as it provides highly accurate ground points that can be used in some instances as ground controls.

In GeoSAR mapping we typically use two types of ground control; a LiDAR profiler on the aircraft, and corner reflectors on the ground. As we fly over an area, our LiDAR profiler collects millions of 3-dimentional points (X,Y,Z) with high fidelity. These points provide a highly accurate dataset to compare and validate the GeoSAR products. Corner Reflectors, on the other hand, are deployed in the project area prior to our data collection. Corner Reflectors are targets constructed of material that is highly reflective to the radar signal. These reflectors are surveyed with a high level of accuracy and then imaged by the radar as we fly over them. They provide an easily identifiable known location in the radar data. Reflector data are used in the least-squares adjustment, removing slight offsets in the data between bands, and as another source of validation. The image below shows a radar reflector used during one of our mapping projects. You will notice that there are four sides to the reflector, allowing the reflector to be imaged from multiple sides during a single collection.

Copy of small_reflector

Ground control points are just one attribute of our unique GeoSAR mapping solution. If you would like to continue the conversation or receive more information please leave a comment. Stay tuned for more GeoSAR capabilities and updates!

GEOSAR FOR BIOMASS MAPPING SOLUTION IN AMAZON FOREST

Friday, June 4th, 2010

GeoSAR continues to make headlines! Fugro Earthdata recently announced that the Blue Moon Fund decided to utilize GeoSAR’s biomass mapping solution in the Amazon Rainforest. GeoSAR’s unique duel band frequencies (X-band and P-band) provide the perfect solution for estimating tropical rainforest biomass. The X-band reflects of the tree tops were the P-band penetrates through the foliage reflecting the near bare Earth, thus producing landscape-level estimates of carbon content in lowland tropical forests. Project deliverables include digital, high-resolution above-ground biomass estimates for the project area, and a map of total carbon storage for evaluation of REDD related baseline. The work will be funded through a grant extended by the Blue Moon Fund and executed through the fund’s partnerships with Wake Forest University (WFU) and NASA’s Jet Propulsion Laboratory (JPL). Please stay tuned for more GeoSAR updates!

GeoSAR 101 Crossword

Friday, April 16th, 2010

This week we decided to have fun with our GeoSAR blog readers! All the answers to the crossword below can be found within the GeoSAR website and/or previous GeoSAR blogs. Good Luck! Answers will be posted next week. Please click on the link below to download the puzzle and clues! For any questions or hints please feel free to write to info@geosar.com.

GeoSAR Crossword Puzzle

From Snow to Sand: The Benefits of Dual-Band IFSAR

Thursday, April 1st, 2010

The conference trail grows longer! At last post, we had just returned from the Alaska Surveying and Mapping Conference in Anchorage where GeoSAR Project Manager Steven Shaffer presented the applications of dual-band IFSAR in arctic and sub-arctic environments. Snow penetration/mapping was part of that discussion. This week we are switching gears—rather dramatically—to the Map Middle East Conference in Dubai where last week GeoSAR Client Program Manager Caroline Tyra presented a paper on the ability of radar to penetrate sand for subsurface mapping.

The overall concept isn’t exactly new. Ground penetrating radar (GPR) technology, which utilizes radar bands in the UHF/VHF frequencies from hand-held or vehicular-based equipment, is a well established technique. It’s the use of remote sensing platforms for subsurface mapping that is gaining ground (no pun intended!). Using satellite and airborne methods, it is possible to provide wide-area coverage of subsurface hydrology and structures for use in mineral exploration and development, infrastructure design, and archeological research.

So where is the science? In the early 1980s, the hyper-arid Bir Safsaf region in southwestern Egypt was mapped using Shutte Radar SIR-A and SIR-B to detect geologic structures covered by layers of sand. Discoveries from that research included fossil river systems. More recent studies have shown the ability of very low-frequency radar, such as P-band, to penetrate depths of 15 meters or more depending on soil composition, radar incidence angles, and soil moisture.

Fugro EarthData has confirmed these P-band findings using GeoSAR during a mission over the Mojave Desert near Edwards Air Force Base. Among other things, the results revealed a mostly submerged geological formation. Subsurface mapping is an area we’ll continue to research given its many implications related to water networks, national security, and heritage management. It’s also one more way that we can help clients maximize the value of their GeoSAR data—by unlocking what we call, “the Power of P”.

Want to continue the conversation? Leave a comment or send us an email at info@geosar.com.

Nobel Prizes: A Win for Geospatial

Friday, October 16th, 2009

This year’s Nobel Prizes are getting a lot of attention. Who hasn’t yet heard the controversy surrounding President Obama’s award of the Peace Prize? You would have to be on a desert island to miss the continuing coverage.

On the science front, the awards are much more straightforward. The Nobel Prize in Physics was awarded to three men whose work in the 1960s made a huge impact on the geospatial industry today. Dr. Charles Kao won for his pioneering role in fiber optic telecommunications. Without his efforts there would have been no internet boom, no online mapping craze, no words being written and read on this blog.

The other two winners, Mr. Willard Boyle and Mr. George Smith, were honored for their creation of the charged-couple device (CCD) in 1969. This technology became the basis for today’s digital cameras, as well as those very high-tech imaging sensors used on satellites and aircraft to map and monitor the Earth’s surface.

Three cheers for these fine contributions and for the committee’s recognition of their importance. The awards are questionable neither in worthiness nor in timing.

Perhaps radar achievements will be recognized next!