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Posts Tagged ‘IFSAR’

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.

Reflections of Singapore – Part 1

Thursday, November 4th, 2010

During our recent travels to Singapore as exhibitors at the GSDI conference, the weather was characteristically warm and humid, and produced heavy cloud cover every hour of every day. No surprises there. However, towards the end of our stay, the city recorded the worst smog since 2003. This was the result of farmers burning off the harvested crops on neighboring Sumatra, mixed in with the warm humid air. The smog was so dense it was difficult see from one side of the street to the other. It occurred to me how difficult it would be to obtain standard geospatial imagery in these conditions; conditions which present no problem for GeoSAR. I also couldn’t help but notice the triple-canopy foliage everywhere that hid so many core infrastructure features. Why in this day of advanced remote sensing technology should a project be severely stalled due to dense vegetation or adverse weather or atmospheric conditions? Users need to be able to obtain accurate geospatial data – both imagery and 3D terrain data – through tropical triple canopy foliage in less than ideal weather conditions. These are a few of the mapping challenges that GeoSAR has successfully overcome.

Night or day, cloudy or clear, GeoSAR collects and delivers the core datasets required to populate your NSDI. Traditional sensors need sunlight for operation, which substantially limits flying time to daylight only and then only when the angle is right, and cloudy and stormy conditions can keep sensors grounded for days, or even weeks. Even panchromatic satellite imagery fails to collect during harsh atmospheric conditions, where clouds and smog hide the earth from these high orbits. Satellite data from radar sensors, while penetrating the clouds offer a much reduced resolution in comparison to GeoSAR; and let’s remember that resolution is an important factor when determining the overall geospatial needs of any NSDI programme.

Night time, bad weather, cloud cover, tree canopy, snow…all of these conditions translate to impossible mapping mission, however GeoSAR tackles these challenges and shows that mapping the impossible is not only possible, but can be done with unprecedented speed and accuracy, anytime, anywhere.

So, are you ready to utilize the world’s largest commercial airborne remote sensing platform? Drop us a line and let us know your needs and we’ll see if we have a solution that fits.

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.

Precision and Accuracy

Thursday, August 26th, 2010

As a key player in the map-making business, Fugro is always engaged in discussions about precision, accuracy, and reliability standards within the geospatial marketplace. Fugro’s GeoSAR system has unique features that ensure quality standards are always met. These features include 4-look acquisition data redundancy as a primary feature of the GeoSAR dual-sided radar configuration, its large side overlap on adjacent flight lines, and its profiling LiDAR. As discussed in our previous “Ground Control” blog post on ground control on the fly.

Let’s first discuss what these quality terms mean in relation to GeoSAR. Accuracy is an absolute term, describing how close the estimated elevation (or position) at a given point is to the true elevation (or position) of that point. Precision is a relative term, describing the quality of the height difference between two points. Reliability is the ability to detect and correct measurement errors, which depends highly on the redundancy of the measurements.

For example, imagine using an old tape measure with 1/8” markings to measure the height of a table at all four corners. Suppose that the measurements are 30-2/8”, 30-1/8”, 29-7/8”, and 30-1/8” – or equivalent to an average of 30-1/8” with a precision of 1/8”. Suddenly, you discover you are off by an inch. That is accuracy. The measurements were inaccurate by about 1”. This example shows that measurements can be very precise, but not necessarily accurate, or they can be accurate, but not precise.

To prevent such errors, the GeoSAR system uses a calibration campaign to resolve systematic errors using precisely surveyed corner reflectors at known locations on a calibration site. A corner reflector is to radar what a benchmark is to photogrammetry—it provides a very precise geospatial correspondence between a radar point and a {X, Y, Z} location on the ground. This is done to ensure the GeoSAR measurements are accurate.

The precision of GeoSAR, or airborne IFSAR, depends on factors such as the aircraft altitude, amount of turbulence, the separation between flight lines, terrain slope, moisture, and other factors. In typical situations, airborne IFSAR is able to measure terrain elevation and geoposition at meter level precision. The accuracy of GeoSAR products depend on a variety of key factors, including the GPS position of the aircraft, the quality of ground control, and the accuracy of the geoid. Similar to GPS, Fugro GeoSAR elevations are measured in ellipsoidal heights and converted to orthometric heights using a geoid model. The more accurate the geoid model, the more accurate the GeoSAR orthometric height will be.

Understanding and applying these key factors is what separates Fugro’s GeoSAR services and products from other service providers. Stay tuned next week when we discuss Resolution and Posting. If you would like to continue this discussion or would like more information, please leave a comment!

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.

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

PurVIEW Expands the GeoSAR User Experience

Monday, February 8th, 2010

In our last post, we wrote about the release of the updated FugroViewer software. This week, the software news continues. As you may have seen in our recent news release, Fugro EarthData and ESRI Canada announced a strategic partnership and global distribution agreement related to ESRI’s PurVIEW mapping software. Why are we talking about it in this blog? Because the implications of this relationship to GeoSAR users is pretty big.

Over the past year, Fugro EarthData and ESRI Canada have worked to modify the PurVIEW software to accommodate use of dual-band IFSAR data. That means users now have a tool that enables them to photogrammetrically capture accurate 3D geospatial information from GeoSAR data (roads, hydrography, cultural features, etc.) directly into their GIS database, as an ArcGIS extension. In a nutshell, it takes “radargrammetry” to a whole new level; no translations, no missing attributes, all native ESRI formats.

We’ve written before about the importance of technology transfer–putting the full power of the data and its potential into the hands of GeoSAR users. PurVIEW exemplifies our commitment to this notion. Within days of the original announcement, we received numerous requests from GeoSAR customers interested in learning more. The demos are lining up!

If you are among those interested, send us an email: info@geosar.com. You can also learn more about PurVIEW at ESRI Canada’s website. We’ll also be on hand at the ESRI Federal User Conference later this month, so look for us there.

The New FugroViewer

Wednesday, January 20th, 2010

Welcome back to On the Radar Screen! As our first entry in 2010, we wanted to spread the word about upgrades to Fugro’s 3D viewing software, FugroViewer. While FugroViewer is a standard deliverable on all GeoSAR projects, it’s also available to anyone (for free!) at www.fugroviewer.com.

FugroViewer

The software was originally released in January 2009 as a tool for technical and non-technical users to view, analyze, and communicate 3D geospatial data. It’s been a big hit. Designed for use with photogrammetric, LiDAR, and IFSAR data, FugroViewer now has hundreds of users in business, government, and university settings.

Upgrades to the new version include: enhanced memory management, additional LiDAR format support (including LAS version 2), additional image format support (including ERDAS Imagine).

Give it a try and let us know what you think!

Remote Sensing and Climate Change Part III: The COP-15 Recap

Wednesday, December 23rd, 2009

As the last entry in our series about remote sensing and climate change, we offer a rundown on COP-15. Overall, the meeting did not deliver on most of the major aims:

– No deadline for a legally-binding agreement
– No greenhouse gas emissions reduction targets for 2020
– No goal for reducing global emissions by 2050
– No deadline for global greenhouse emissions to reach their peak
– No mention of aviation and shipping (specific sectoral agreement)

But that’s not to say COP-15 was a failure. There was some progress on monitoring, reporting, and verification; REDD; financing; and technology transfer. Details on each of these topics follow.

Monitoring, reporting, and verification: China, India, and other developing nations are to publish their emissions curbing commitments in annexes to a new global agreement. They would then communicate progress to those goals according to internationally agreed upon standards.

REDD: On deforestation, there should be the “immediate establishment of a mechanism, including REDD-plus” to mobilize capital from developed countries for “reducing emissions from deforestation and forest degradation” and enhancing “removals of greenhouse gas emission by forests”.

Financing: Developed countries are to “support a goal of mobilizing jointly 100 billion dollars a year by 2020 to address the needs of developing countries”. This funding will come from a wide variety of sources, public and private, bilateral and multilateral, including alternative sources of finance. There will also be 30 billion dollars made available over the 3-year period of 2010 to 2012, balanced between climate change adaptation and emissions mitigation. Further, a new UN Framework Convention on Climate Change mechanism called the Copenhagen Green Climate Fund will be established to support funded “projects, programs, and policies” on mitigation, REDD-plus, adaptation, capacity building, technology development and transfer.

Technology transfer: A new technology mechanism will also be established to further accelerate technology development and transfer under a country-by-country approach. (This is in contrast to the existing CDM which takes a project-based approach.)

So what does this mean for remote sensing? Without a binding agreement, it may still be too early to tell. But cautiously speaking, it appears we are headed down a path where REDD (or REDD-plus) will be properly funded, which means the remote sensing technologies we discussed last week will be used to help measure and monitor forest carbon.

This, along with the emphasis on technology transfer holds real promise. By increasing the number of users skilled in the science and application of geospatial data, climate change policy can impact countless other areas of a developing nation’s existence, from infrastructure planning to emergency response to economic development. Now that’s something to be optimistic about in the New Year.

Remote Sensing and Climate Change Part II: Making REDD Work

Friday, December 18th, 2009

As heads of state and other government leaders enter the final rounds of the COP-15 climate change talks, many key issues remain unresolved. The target rate of emissions reductions by wealthy nations, the amount of aid to poor nations, and monitoring compliance are at the crux of the slow-moving negotiations.

It’s the monitoring piece where geospatial comes into play. As addressed in our last entry about the REDD initiative, several remote sensing methodologies can contribute to large-area forest carbon measurement and monitoring, each with unique benefits. This week we are taking a closer look, reviewing the top-three technologies and briefly exploring their strengths and weaknesses:

Optical imaging: Offering low-cost, repeat coverage acquisition over large project areas, satellite-based hyperspectral and multispectral imagery has shown some potential for biomass estimation. Systems with sophisticated scheduling enable around 70 percent cloud-free coverage in equatorial regions, thereby reducing weather obstacles. And while satellite is proving a good source for monitoring REDD sites in Brazil, it alone isn’t a good source for carbon measurement. For that, you need tree height data and optical imagery provides only canopy-level information.

LiDAR mapping: Foresters have long used LiDAR systems to measure forest canopy and vertical structures. As an active sensor, airborne LiDAR data can be acquired night or day, providing very dense and accurate datasets. The downside to this approach is the high cost of acquisition and processing over large areas. Satellite-based LiDAR systems may help control these costs with wide area coverage and automated processing capabilities. The Geoscience Laser Altimeter System (GLAS) on NASA’s Ice, Cloud, and Land Elevation Satellite (ICESat) is one such example. Some studies show promising results, though clouds are an issue, and so is a general lack of ground height data. So, again, LiDAR may be a technology best suited for monitoring practices.

IFSAR mapping: Low frequency, long bandwidth IFSAR is an all-weather technology that provides high foliage penetration for near bare-earth elevation data, even in dense forests. When combined with higher frequency, short bandwidth IFSAR (which provides elevations of top surfaces), it is possible to detect the heights of individual trees within a forest. That’s the beauty of GeoSAR; it offers both views of the forest simultaneously and can also be used to identify forest type. This data, combined with biomass information on individual tree species, enables efficient and accurate forest carbon content estimations.

But GeoSAR isn’t a silver bullet. Given the relative high cost of airborne acquisitions in comparison to satellite sensors, IFSAR isn’t an ideal monitoring solution. It’s role is to provide accurate baseline information from which REDD programs can be evaluated.

Fugro EarthData published an article about using dual-band IFSAR for carbon accounting in the July issue of PE&RS. It’s a good source of information about remote sensing and climate change monitoring. And, if you want to catch the latest on COP-15, here’s a live web cast of the proceedings.

Next week: COP-15 wrap-up and its implications for remote sensing. Check back then!