Best Practices (Raw Data)

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Best practices or the idea of following a “best practice work flow” is a concept that comes up often in all aspects of surveying and engineering. Whether it is collecting field data, designing a subdivision, or producing a final site plan, people would like to know the best method to achieve their final goal. The question “what is the best practice for………?” is a question that is asked Carlson sales and support staff on a regular basis.

The truth of the matter, however, is that a well-established work flow for one firm or individual may not work well for another. Furthermore, each type of job, especially when it comes to surveying, may require a different methodology of gathering and processing data. It is difficult to create a “one size fits all” type of work flow. With that in mind, I will focus this blog on sharing some thoughts and experiences on collecting and processing field data using Carlson Survey.

Establish Standards
One of the hardest aspects of learning to survey is to understand the level of precession that is required for each individual survey. If you are performing a small backyard topographic survey, you do not need to follow the same field procedures as laying out steel for a high rise building. Likewise the processing of the field data may change for different types of surveys. The type of traverse adjustment, the use of coordinate files, and handling multiple raw files are all considerations for each survey. The first step in determining a best practice is to define the desired outcome. Essentially, do you need to post process your data or not?

Define the Work Flow

In general, there are two options for getting survey data from the data collector into a drawing file. The decision between the two options basically boils down to whether or not you are going to adjust or otherwise manipulate your raw data. If you plan on editing the data or perhaps perform a compass rule or least squares adjustment, you will want to run the data through another program such as Carlson’s Edit Process Raw, a data editor. If you are using Carlson’s SurvCE or SurvPC, you can directly read the RW5 file that automatically gets created for every job in this editor. If you are using another data collector, there are many format import options available.

Once in the editor, there are multiple adjustment options (including none), for adjusting the data set.

The Best least squares adjustment option is SurvNET
If you do not desire to adjust the data set at all, you can simply export an ASCII file containing the final coordinates for the job and import them directly into the coordinate file from the Import/Export command in the Points menu.

For SurvCE/PC users, there is also the option to just download the CRD file directly from the data collector and use it. I will discuss using multiple coordinate files later in this blog.

Handling Multiple Data Sets
Any work flow can seem to work fine for small jobs that are completed in a single day. It becomes a bit trickier when multiple days of field work are required, especially when the project schedule dictates the need to be working on the drawing while the field work is still being gathered. I again reduce this to two basic options: utilizing the raw data editor or just importing points directly into the coordinate file.

Using Raw Files
If you use multiple raw files you can process them one at a time into the coordinate file. This method creates a simple way of keeping each day’s data in an individual raw (RW5) file while processing into a single project coordinate file. The program will present a warning if duplicate point numbers have been used between data sets and give you options such as overwriting or renumbering the points. Using the raw data editor will not only perform adjustments such as compass rule, but also create data reports, append raw files, renumber points, and even adjust measurements in case of setting a prism constant incorrectly.

The Raw Data Editor also has options to set hierarchy over control points. This option helps with what for me was a fairly frequent occurrence when gathering new information on an existing project. A quick as-built of a project under construction or multiple crews surveying a large project are both examples of having to handle field data in a less than traditional manner.

Example:
A survey is performed using assumed control points number 1 and 2. However, actual grid coordinates are known for these points back in the office.

The correct coordinates for points 1 and 2 are already in the project coordinate file from a previous survey. While in the Raw Data Editor dialog box, from the Edit pulldown menu, select Convert Points to Note Records.

This process changes each point record (PT) to a note record (DS). In doing so, when processing the data, the program will pull the coordinates for points 1 and 2 from the coordinate file instead of from the raw data. This process allows a lot of flexibility when collecting data and an easy way to make a coordinate shift N, E, or Z.

Note the option for Point Protection when processing the data.

An important feature to be aware of is that using SurvNET allows you to process multiple raw files all at once instead of one at a time.

Another great feature of the Raw Data Editor is the ability to create Point Groups from the data contained therein.

This is accomplished from the Tools pulldown menu.

Using Point Groups is a great way to segregate and control the data between data sets. You will notice Point Groups as an option in virtually every program when selecting points including Draw/Locate Points and Draw Field to Finish. You can easily create a separate point group for each day’s field work and then take advantage of all of the point group tools available.

Using ASCII Files
If you prefer to import multiple ASCII files directly into the coordinate file, you can easily accomplish that by using the Import/Export function in the Points menu.

Again, notice the options for Point Protection and creating Point Groups. Other notable options are limit the point range to import, renumber points, and process multiple files.

Multiple Coordinate Files
Another option to handle data is by using multiple coordinate files. Although this is not my personal preferred method, I have run into several surveyors who tend to utilize more than one coordinate file. To use any coordinate file, just simply open one and add the points to your drawing via Draw/Locate Points or Field to Finish. The program draws the points and links the project to that coordinate file. You can then manage the linking between the drawing and coordinate files through the Point Entity CRD File Links Manager found in the Coordinate File Utilities dialog box.

When using this option, it should be obvious to most users that caution must be observed. The user needs to be aware that if points are manipulated in a drawing using tools such as Align or Translate Points, all points selected will be altered in their respective coordinate files. In other words, you can be updating multiple coordinate files at the same time. If the user is unaware of this fact, serious mistakes can happen.

An alternative to just simply opening and using multiple coordinate files is to use a single base coordinate file to work with and merging any other coordinate file into it. This can be accomplished with the Copy/Merge CRD File option in the same Coordinate File Utilities dialog box.

When importing points from another coordinate file you again have Point Protection as well as the option to create a Point Group.

The advantage to this method is that you will draw or manipulate points from a single coordinate file without affecting others. It tends to simplify the process in a multiple-user setting.

Drawing with Field to Finish
The most efficient way of getting points into a drawing is by using the Field to Finish program. One of the problems people have shared is that by default, when you draw using Field to Finish, the program erases the existing points, symbols, and linework and redraws them. This can be controlled through settings in the Draw Field to Finish dialog box.

Note the options to control whether or not the previous entities will be erased. It is best to have this set to Erase Existing to prevent duplicate points in your drawing. To control which points are drawn, set the point range appropriately, or better yet, use the Point Group option. This allows you to work on a drawing knowing that more data will be added without upsetting any work you had already completed.

These are just some options for handling data that have worked well for me. Try out options and see what works best for you and/or your firm.

Have you tried Carlson Academy?

An online learning tool to help you get the most out of your Carlson software.

How to Begin
To begin learning Carlson, go to account.carlsonsw.com. If you already have an account for Coordinate Cloud, Carlson Community, or PhotoCapture, you can simply use those login credentials. If not, create a new account.

The criteria for use are to have up-to-date software and to have your email address included in the Carlson database. It is also available for those who are demoing the software.
If you are not up-to-date with your software, you can get current at:
www.carlsonsw.com/where-to-purchase/maintenance

Doug

Let’s Grow Together.

Douglas L. Aaberg, PLS
Survey Product Manager
P)617-393-2300×419
daaberg@carlsonsw.com

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