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Building An Image |
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By David Oltman |
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A new tool designed to help winegrape growers with many of the critical decisions for
production a premium quality crop will complete its work without ever entering the
vineyard. Instead, this piece of equipment - a digital camera that provides a multi-band spectral image directly related to levels of vigor in the vine canopy - will do its job thousands of feet in the air. The technology is being offered on the North Coast this year through a collaborative effort by the National Aeronautics and Space Administration (NASA), Terra Spase, Winegrow and Robert Mondavi Winery. NASA has coordinated the program as part of its goal to make precision farming tools such as remote sensing more accessible to winegrape growers. The effort is being called the Canopy Remote-sensing for Uniformly Segmented Harvest (CRUSH) program and is designed to offer wineries and vineyard owners specially processed imagery that will aid them in the 1997 harvest. "Winegrape growers who are striving for a very high quality product should definitely investigate this program," says Paul Skinner, president of Terra Spase, a Napa company that is processing the remotely sensed data this year. "This imagery should provide winemakers and vineyard managers with the ability to harvest grapes at a certain uniform level." The CRUSH project included a flyover of North Coast vineyards in late July to compile images taken by digital cameras aboard a single engine aircraft flying at 14,000 feet. The images are directly related to the amount of vineyard canopy reflecting solar energy from the ground. The CRUSH project is an outgrowth of NASA's 1995 Grapevine Remote-sensing Analysis of Phylloxera Early Stress (GRAPES) project in which the agency used high resolution digital imagery to track the spread of that deadly root louse in North Coast vineyards. The new project is part of an effort by NASA to transfer the technology and data processing techniques learned in GRAPES to the private sector and allow it to be disseminated to as many segments of the winegrape industry as possible. "Many of the value-added processes that we developed for phylloxera detection in the GRAPES project are also relevant to this more generic application," says Lee Johnson, a remote sensing scientist stationed at NASA Ames Research Center in Mountain View. "In that project, we were basically producing maps of canopy density, which can also be useful in this new effort." The key to the CRUSH project is being able to go beyond using the imagery for phylloxera detection and providing winegrape growers with a tool that will show them how their vines are performing and how that information can be used to make harvesting decisions. In addition, those involved in the project are hoping to expand it next year to include more flights that can gather data for use throughout the growing season. With NASA's assistance, processing techniques have been implemented at Terra Spase to analyze the data gathered in the vineyard flyovers. The imagery for the CRUSH project includes data gathered by the ADAR 5500 digital camera system through Positive Systems, Inc. of Whitefish, Mont. The ADAR system collects digital data in the blue, green, red and infrared energy bands from the vines 14,000 feet below. The imagery is based on pixels (a grid pattern of squares) with a two meter resolution. Each pixel has four data values associated with it - one value for each band collected. Since the data is collected digitally, there are numerical data attached to the picture. The red and infrared bands are very important spectral bands in green plants for the study of plant stress and leaf density. "The camera is detecting energy within narrow bands of the spectrum of light and we have the ability to focus on those bands that are very sensitive to specific plant characteristics, such as water status and chlorophyll levels," Skinner says. Terra Spase can classify reflectance levels and assign them a specific color that correlates directly to the amount of vine canopy detected. The processing techniques begin with what is called a Normalized Difference Vegetative Index (NDVI), which include values directly related to the amount of leaf area in the vine canopy. The values of the NDVI are then organized as separate classes. The final processed data produced by Terra Spase shows cabopy density in increasing levels displayed in nine color classes going from blue, green, red and yellow. Blue represents very low canopy density or bare soil, while yellow represents the highest canopy density. The data can also be processed to create an image similar to color infrared and normal color photographs. The images obtained in the 1995 GRAPES project are the starting point for a plan by the Robert Mondavi Winery to use remote sensing technology to determine vine performance in chardonnay and pinot noir vineyards in the Carneros region. Mondavi and NASA have set up the study plots as part of an effort to take ground-based measurements and compare them to what is being detected in the remotely sensed images. "We will be taking chlorophyll measurements to see how green the leaves are and also some leaf water potential readings in those vineyards;" says Daniel Bosch, vineyard technical manager for Mondavi. "That will allow us to measure how stressed the vines are in those areas - we were able to see some pretty dramatic differences in those vineyards already based on what the 1995 imagery showed us." Using that imagery gathered for the GRAPES project, Mondavi was able to determine that areas showing more vine vigor in a chardonnay vineyard had very high quality grapes, making them eligible for the winery's reserve chardonnay program, Bosch says. "The areas that showed less vigor could not be used for our reserve program - the quality of the grapes we harvested pretty much matched with the levels of vigor recorded in the imagery." This year Mondavi will be gathering more information, including Brix (sugar) and pH level measurements in the grapes and light interception measurements for canopy density as part of the ground study component of the CRUSH project. Those readings will be used to determine how data compiled in the vineyard correlates to what is being seen in the imagery in terms of vine canopy vigor levels. "We have very few vineyards that have phylloxera, so our interest in obtaining this imagery now goes beyond that type of detection work and moving on to being able to improve our wine quality," Bosch says. "We believe we have been able to improve the quality of wine in those vineyards where we have tracked vine canopy vigor using this type of imagery." Using the 1995 images, Mondavi was able to guide its sampling program close to harvest to determine that contrasts in vine canopy density also related to differences in how the fruit was ripening throughout the vineyard. It was found that grapes on the more vigorous vines were less mature at that time, while the less vigorous vines were already passing their optimum harvest point. Being able to detect those differences based on levels of cabopy vigor seen in the remotely sensed imagery is the key to CRUSH project's ability to provide growers with a tool to help them make harvesting decisions, Skinner says. "Instead of getting an average of overripe frit and under ripe fruit, this imagery will help a grower to harvest grapes at their optimum level of ripeness," Skinner says. "A grower will then be able to harvest the rest of the fruit as it ripens and not pick across blocks that are not similar in maturity." The CRUSH project is designed specifically to segment areas within targeted vineyards according to levels of grape maturity, says Johnson. With the imagery in hand, a grower could harvest all grapes within a block and put them in separate wine lots based on maturity or harvest areas within that block at different times depending on maturity levels, he adds. "The basic goal of the CRUSH project is to disseminate the technology to the private industry, which is distinct from the research effort that was the main component of the GRAPES project," Johnson says. "This one has very much a technology transfer slant to it." NASA participation in the CRUSH project was sponsored by the NASA Ames commercial technology office. Funding was allocated for a single North Coast flyover. "What I like about this project, and what I believe shows its commercial potential, is that all of our collaborators are participating at their own cost," Johnson says. Those participants include Terra Spase, Mondavi and Winegrow, a winery and vineyard consulting firm in Healdsburg. "One of our goals with the CRUSH project is to stimulate demand on the art of the wine industry for remote sensing services," Johnson says. "We also want to enhance the capability of the private sector to provide these services to the industry." The study plots set up in the Mondavi vineyard are designed specifically to stimulate demand for the technology by showing how ground-based measurements cam be used in conjunction with the remotely |
sensed imagery as a
guide to how vines are performing, Johnson says. "This demonstration involves going out in the field and taking ground measurements that will help us understand the patterns that we are seeing in the imagery," Johnson says. The ground measurements are designed to supply information about canopy density, chlorophyll concentration, water stress in the plant and grape maturity, he adds. "When this is all over, we will have a body of evidence that says these differences that we are seeing in the imagery are in fact real - that they can be attributed to one or more of those four key indicators," Johnson says. Mondavi will make separate wine lots from grapes harvested according to what is seen in the imagery, evaluate the wines in a taste test and then perform a cost-benefit analysis to assess the overall value of such a remote sensing program, he adds. "Our hope is that what Mondavi is doing in the study plot will lead to a more efficient deployment of those ground sampling units and help us better understand what we are seeing in the imagery," Johnson says. "This project has a potentially high value to the wine industry and is not just tied to a particular infestation or blight in the vineyard that is here today and gone tomorrow." Phil Freese, president of Winegrow and a member of the team that worked on development of the CRUSH project, agrees that its biggest value will come in the transfer of technology to the private sector and in being able to move beyond serving as a tool only for phylloxera detection. "We already know, for example, that in Napa County, the phylloxera detection work and the replanting program is pretty much under control," Freese says. "What we are hoping to do now is find a way to use this technology to detect stress, or different sizes of vine canopy, by looking down from the top." Freese, who worked with NASA on the GRAPES project, serves as a consultant to the wine industry, helping wineries match their needs with what is being harvested in the vineyard in order to create specific wine styles. While he is not a direct user or service provider for the technology, he will be working closely with those involved in the CRUSH project. "I will bring people in who may be users and at some point may become a user of the technology myself," Freese says. "At this point I am serving as an advisor, saying to those who are involved in the project that if we can tweak the product in such a way, the market is going to find it more attractive." Freese says he believes the technology will allow the grape grower and winemaker to assess vine performance and identigy areas within the vineyards that may be facing stress and are therefore ripening the fruit differently than other areas. The winemaker and grape grower can identify those areas and make more informed harvesting decisions, he adds. "I am really bullish on this technology - I think it is another tool to put into people's hands that will enable them to sample areas of their vineyard at the optimum time and allow them to make the highest quality wines possible," Freese says. "Where we are really going with this is toward precision farming, and this is a tool that fits in with that overall goal." The precision farming component of the CRUSH project also includes the use of Global Positioning System (GPS) and GIS technology in conjunction with the multi-band spectral imagery gathered in the flyover. Some of the imagery collected and processed by Terra Spase will be registered according to GPS data, including latitude and longitude readings in the vineyard, that is supplied by a satellite orbiting the earth. The ability to register the imagery allows the remotely sensed data to be overlaid with a GIS program that can include soil maps, vineyard contours, rainfall measurements and other weather-related information. The information can be used to initiate site specific cultural practices, including fertilizer and pesticide applications, leaf removal and irrigation scheduling. The GIS information is part of what Terra Spase offers winegrape growers through Terroir, a software package developed by Skinner that reveals the spatial variability in soil chemical and physical characteristics. "Our maps show areas of high and low pH, potassium and phosphorous, as well as clay and sand percentages," Skinner says. "We have coined the term 'soil vigor potential' to describe the effect of up to 20 different soil measurements on vine growth." With maps showing soil characteristics throughout a vineyard layered on top of the remotely sensed imagery revealing canopy vigor, growers will have an even better way of determining vine performance, Skinner says. "We can put the two together and determine the correlation between high soil vigor potential at specific sites and canopy density," Skinner says. "That is the really powerful part of the technology we have developed as part of the CRUSH project - it adds another layer of what we are already describing, which will allow us to measure how the vines are performing." The cost for supplying remotely sensed imagery to winegrape growers ranges from $10 to $30 an acre, Skinner says. That figure is based on a sliding scale Terra Spase has established for processing and delivering the imagery according to the amount of acres being covered for a client. At Hanzell Vineyards near Sonoma, the technology that combines information gathered on the ground with what can be detected in the remotely sensed imagery should be helpful in monitoring different cultural practices, according to Bob Sessions, Hanzell winemaker and president. "We are trying out some different ways of growing our grapes this year because we have such a bountiful crop," Sessions says. A block of chardonnay vines on the Hanzell property is receiving three different treatments, with grapes from each treatment being harvested separately and crushed into individual wine lots. In one area of the vineyard, the grapes were thinned but the vines received no irrigation water, while another area included vines that were thinned and provided water through a drip irrigation line. A third area was set aside where no thinning was done, but irrigation water was applied. Sessions has been a Terra Spase client, using maps showing soil variability throughout the Hanzell vineyards to reveal relative vine strength and make determinations about what varieties should be planted in new vineyards. The remotely sensed imagery should be another valuable tool for making cultural decisions in the vineyard, he adds. "From hearing what Paul said about the program, I was easily convinced about its possibilities and was sold on the idea," Sessions says. "I told them to sign me up for the program." Using the remotely sensed imagery to investigate how vines respond to different cultural practices, such as those being undertaken at Hanzell, should add to the value of the technology, according to Susan Mahler of Terra Spase. "I think this imagery is going to be a very effective tool for growers - it's just a matter of helping them to understand this type of data and how to apply it to their situation," Mahler says. Many growers use color infrared (CIR) photographs to depict variation in their vineyards, but that type of imagery is limited in information contact and some growers are beginning to question the usefulness of the CIR photos, she adds. "The processing and display techniques we are able to do with this digital imagery takes the technology to a new level, where it is much more useful than CIR photos," Mahler says. "We have the numerical data in place and are able to process this information and quantitatively assign it to a wide range of colors, enabling growers to gain a lot of insight to variations in the field." As the data are processed and disseminated as part of the CRUSH project, those involved in its development are already looking ahead to other potential uses for the technology. It is hoped that if enough interest is created, there will be an opportunity to conduct more flyovers and gather information about vine canopy vigor throughout the growing season. In addition to possible further commercial flights using fixed wing aircraft, there is an effort by some private companies to launch satellites in the near future that could be used to gather information as part of a program to supply remotely sensed crop imagery. "People have been very enthusiastic about the CRUSH project, but when we tell them we could have more flights and go even earlier in the season, they get even more excited," Skinner says. "There is a perception that the earlier you know something about canopy vigor, the better off you will be." With earlier and more frequent flights, growers could have information in their hands on a weekly basis to make decisions throughout the season, Skinner says. "We may be able to see such things as vines being stressed by lack of water or a pest infestation before it can be seen on the ground - it will allow growers to make some critical decisions in a very timely manner." |
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