SVS
Figure 1: SVS graphical output
SVS is an abbreviation for Stand Visualization System. It is a computer program that graphically represents the characteristics of a given stand of trees (see Figure 1). The program can represent trees, shrubs, snags, fallen timber, and other various objects in a three-dimensional view. Using the images produced by SVS, forest managers and engineers can more easily see what type of silvicultural activities may need to take place in the near future.
The use of SVS for the Washougal harvest and transportation plan is mainly for visualization. SVS will have nothing to do with the final plan, but will serve as a reference to see how an individual stand may look like in the present and 30 years from now. Being able to visually see what the density of a stand looks like can help in deciding the type of harvest equipment to use or if any thinning needs to take place prior to final harvest.
Each stand that will be harvested will be visually represented by 2 images. One image will be the replica of the stand today and the other image will be the same stand in the year 2028. Accompanying the images are graphs of the distributions of dbh's and height's of the trees in the stand. Hopefully this data will be useful to the overall project.
Data Needed
In order for SVS to replicate trees in a stand, the program needs stand table information.
SVS requires two types of data:
- stand table
- plant form definitions
The stand table consists of the following parameters:
- Species
- Diameter
- Height
- Crown ratio
- Crown radius
- Status (dead, alive, or fallen)
- Plant class
- Crown Class
- Expansion factor (like the stand densities)
* SVS can use more parameters than the ones mentioned above, however they are unnecessary for our uses at this time.
Most of the data above can be found in an average stand table, however crown ratio, crown radius, status, plant class, and crown class are sometimes hard to find.
Crown Ratio is the percentage of crown on the tree stem. For example, if a tree has a crown ratio of 0.50 then the crown extends half-way down the tree stem. Depending upon the density and some equations for crown radius, crown ratio can be determined using available data.
Crown Radius is the radius of the foliage on top of the tree. SVS calculates that number if it is inputted as 0.0. Therefore, this number is not important unless the data is available.
Status is a number that only SVS uses. A 1 is a live tree, a 0 is a dead tree, etc. Please refer to the SVS manual for more information.
Plant Class and Crown Class are also numbers that only SVS uses. Those values can be inputted as zero and SVS will calculate them on its own.
The plant form definitions are the descriptive characteristics of the different types of plants found in the given area. In the program, there is a "tree designer" where the user may actually create a tree of his/her choice. Using a list of the different tree species SVS represents, the user may specify the overall growth form of the tree. This consists of geometry and number of branches or leaves, color of stem, branches and foliage. However, for most tree species there is already a programmed definition of its geometry. Therefore plant form definitions are not important in our harvest and transportation plan.
Converting Data to SVS Format
Once all the data has been collected, it must be formatted so it can be made into an SVS file. Using a program such as Microsoft Word or WordPad the data is saved in the format as the sample below.
SVS will ignore any line that starts with a semi-colon. The data needs to be separated by a space and typed in the order as it appears in the above example. After the data has been saved as a Text-Only file in the SVS directory, the user needs to open the DOS prompt. Go into the SVS directory and run TBL2SVS. This program converts a text file to an SVS file. At the DOS prompt type:
TBL2SVS example.txt
The program will then convert the text file to example.svs. After the SVS file has been created, it can be opened in the SVS program.
Other Ways to Make an SVS File
If FVS or LMS programs are being utilized for the project, the above process of making an SVS file can be ignored. LMS will automatically create an SVS file after running the growth model. All that is needed is to transfer the SVS file into the SVS directory. However, LMS and FVS only create the future SVS file. If the present stand needs to be represented in SVS, then the procedure described in "Converting Data to SVS Format" must be followed.
Once all the inputs have been exported into SVS, the program creates a graphical image of the stand. The user can view the image at different perspectives and elevations. The distribution of the dbh's and height's can also be graphed alongside the stand image.
Below are the images of two stands in the harvest and planning area. The first image is the stand in the year 1998 and the second image is the stand in the year 2028.
Figure 2: Stand 270079 in 1998
Figure 3: Stand 270079 in 2028
Figure 4: Stand 270096 in 1998
Figure 5: Stand 270096 in 2028
The stand images above may not be a lot of help when it comes to this harvest and transportation planning project, but that does not mean they are useless. They provide a better understanding of the current and future stand structure. Next quarter in FE 450 we might have to plan some type of silvicultural activity. Whether the activity be a thinning or habitat cut, the image of what the stand might look like after the activity is completed might be important. SVS can be an important tool in any forest activity that may visually affect the aesthetics of the current stand.
There are many more options that can be utilized in SVS. It is not a complicated program, but it does take time to learn its capabilities and functions. If you would like a more detailed description of SVS or if you would like to learn more about the program please go the forest-engineering cooperative study page. On that page you can also download the program and manual. Have fun!
SVS manual in BLD 389
McGaughey, Robert J., SVS Notes, http://forsys.cfr.washington.edu/svs.html
McGaughey, Robert J., Personnel Interview, March 9, 1998.
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If you have any questions about SVS or its abilities please feel free to email me at jcpascal@u.washington.edu
Created By: Jon Pascal
Last Updated: March 15, 1998
