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Peaks and pitfalls of field to finish data collection technology.This article is intended to convey an insight to some of the technology you may already have invested in, which may not be used to its full potential. It may help you if you are apprehensive to dip into hardware for your crew.
Let’s take a step back and think about the process of gathering topographic data. I’m sure many of you can recall laying the base line with a theodolite, measuring right angle offsets to the desired features, recording them in a field book and plotting them on grid paper. These methods have been proven, accurate, quick and cheap. Or have they?
Field to Finish ConceptIn today’s marketplace, major clients request a digital copy of the work including a point list as part of their deliverables. You may ask your client what type of software deliverables they seek, what version of the software they require and if they have a drawing environment to import data.
Data must be gathered electronically so it can be downloaded, processed and mapped to a point where minor editing is performed. No topographic survey processed will ever be 100 percent complete initially from the field. But depending on your collection methodology, descriptors and software, you can achieve nearly 80 percent completion. The remaining 20 percent would mainly be edits within text orientation, additional editing, notes, title blocks, etc.
Software ConsiderationsIf you are thinking about diving into some field to finish software, what would be some key factors to consider?
Today there is about a dozen types of software with the field to finish capability. But before software of this nature came to be, a few co-workers and I from Wendel Duchscherer, a consulting firm in New York, wrote an Autolisp routine to extract data from an ASCII file to perform line connectivity and symbol insertion. This proved to be tedious at the time, but the time invested has been paid back many times over since it was first implemented. Other individuals have created similar routines that may be downloaded from the Internet. However, most of these appear limited in their abilities.
When considering a software product, your clientele would surely be a main concern. If your core work is DOT (department of transportation) related, your decision may be limited to what the agency recommends or requires. In our case, the DOT agency publishes minimum software requirements of which InRoads Survey by Bentley Systems (Exton, Pa.) is noted. This particular software has tables that can to be created or tailored to a particular method of descriptions along with base mapping environments. This can be a tedious setup at first. Or in some cases, your client may have already set this up. With our DOT, feature tables and symbology have already been created for distribution. This ensures less re-work because the client makes sure of consistency.
It seems the most commonly used drafting software are ACAD and Microstation, but other products have their own drafting engines, such as TrimMap (Trimble, Sunnyvale, Calif.) and SMI Plot (Surveyors Module International, Church Hill, Tenn). Both are excellent software, but with any software, make sure your Export or Save As routines allow you to save to a particular version of software. Another important thing to remember: if you perform a conversion, do an integrity check with your data in the environment you saved.
Cost: I’m sure some of you thought of this as the first factor for deciding on a software product. The cost of each software will depend on the amount of training time you’re willing to absorb after the initial software cost. If your survey business is moving from base line offset topo to field automation, it is obvious you’re going to have a significant learning curve.
Comments and recommendationsWe at Wendel Duchscherer have been able to experiment with a few of the software products available. Softdesk Land Development (Autodesk Inc., San Rafael, Calif.) and In-Roads Survey are two we found best suited to our needs.
When we considered these products, we wanted to be certain that specific tasks could be performed: How can I download my data collector? What type of files can I read? What applications can I perform? Whatever you choose, make sure you do your homework. A good resource is the Internet, both for the software manufacturer and user group discussions.
Some of the experiences we’ve had with software were hardware requirements. Make sure you have a solid Windows system that includes MSDOS, and has plenty of drive space, speed and RAM. If your system is more than five years old, it may be time to bequeath the old machine to your five-year-old nephew.
Implementing your softwareSo you’ve purchased some software …
Make certain to get some outside support. There will always be that one question that will haunt your day. Don’t fully rely on the books that are sent or on the software “help.”
If your sales representative delivered a brand-new box of “ABC” software and gave you a free hat to boot, be wary. Before you open that box, sit down together and agree on some common guidelines on how your field crews are going to gather data. Set standards. Chances are your standards are going to be driven by your client specifications. As I mentioned earlier, our DOT agency already has field descriptions completed, so it’s just a matter of getting their updated list. If you don’t have a consistent list, now is the time to get one. One of the worst time killers is trying to decipher field codes. One day someone may describe a shot as “bs” for bit shoulder, and on the next day that same person gives you “bs” for bottom of slope. C’mon, what’s with all the bs?
Do’s and don’ts of data collection methodologyLet’s assume you have a solid control network established and you are ready to go. You drive two hours, talk about your game plan, how much you plan to get done, the job requirements, what you’ll have for lunch. You get to the jobsite to set up and what happens? You forgot a piece of equipment, the batteries were left on the charger, the wrong DC cable is in the box. A good day of DC requires you to incorporate a checklist within your standards—no matter how redundant it seems.
FieldBefore setup, get together with your crew and communicate! Your instrument person is not a mind reader; share the game plan. If you have to measure your sections or set up safety gear, talk along the way. Your instrument operator will build confidence and ease in knowing what lies ahead.
Your data collector should be properly set to the correct instrument. The instrument settings should be consistent with your DC settings. If you use a symbol library in your DC, make sure it is the right one for the job. I recommend a 3"x5" laminated card with the most common descriptions. Sure some will seem redundant, but every job seems to have one descriptor that may have slipped your mind.
Gathering data by the crew seems to be organized chaos at times. Whether I pace or measure sections, I like to start with these first. I’ll gather three sections [Every topo job for which you generate a DTM should have a section interval or grid. This will enable your TIN (Triangular Irregular Network) to be consistent and more accurate.] After a few sections are gathered, I’ll gather the miscellaneous topo in between, then move on to the next set of sections.
When gathering sections you’re also gathering linear features. Each linear feature will have its own designation. This is used for processing and creating your DTM. Sometimes I’ll mark each item (especially with “busy” topo) to keep track. But if you start a new file in the same job, start your feature numbers over again.
When gathering linear features, don’t backtrack. Remember point numbers count. This statement is a testament to eliminate your linear feature from zigzagging back and forth. If this is how you’re gathering data, I assure you will change. Software looks at the linear feature along with the point number it is being stored as.
Also, with gathering data there are some instances where you can locate two or three features with one shot. Say a top of slope ends at the base of a utility pole with a guy wire 10' to the west. I would type “TS4 UTP GUY-10W.”
Keep your descriptions short. You may want to assign attributes to your descriptions (e.g. with the shot you may be able to go one step further and enter more specific information such as pole numbers, invert data, etc.), but don’t use more than 16 characters.
Before you break down, take a quick look at your data, especially the last few shots. One time my instrument operator had not realized the DC ran out of memory! We were still able to gather data, but it wasn’t written to the memory card. We discovered, luckily, we only had missed about 10 shots, so re-shooting them took about 10 minutes instead of two hours. It pays to be somewhat skeptical of your data, so you should check often.
Post-Field and Data ProcessingDownload your data as soon as possible. I tend to have more confidence when I know that I have a copy of the data somewhere other than in the DC. Ask yourself, what is six hours of data worth? Can I afford to take another five minutes to download? Be sure to download your raw file; this is the evidence of your day. If you need to regenerate coordinate values because of a datum change or a blown height, it is best to revise at this point.
Now that you have your field data, you are ready to import for processing to create your map. The software products are all basically the same on this function. The first and foremost item to adhere to is the standard of your descriptions collected in the field and how your software descriptions in the office are setup. They have to be in sync; otherwise you may end up with a point plot on the screen with nothing drawn.
The format I like to use is the tried-and-true format (ASCII). Your data collection software will allow you to save to an ASCII format or TXT, except for the three-letter file extension for which you may have to rename your xxx.txt to xxx.asc to make your software work.
Software products such as InRoads Survey allow you to generate your map from many different types of data collector output formats, but ASCII is one of these as well. Simply open your specific feature table and symbol library and import your file. On the screen in literally less than one minute you will see your field work in action and drawn onto the screen with lines and symbols.
If your data looks good, you’re ready to start editing. Major drafting items may be symbol orientation, text, title block and legend. With some more experience, some of these previously mentioned items could be cut down. The software can automatically create legends because it knows what symbols and lines have been inserted into your drawing. The default drawing you use to insert your data may already include a title block. Attributes can be assigned to your field descriptions so they can write the whole un-abbreviated description into your drawing.