SNAP is designed to assist in the scheduling and transportation planning for harvest areas. Two versions of SNAP are available, SNAP II (Ver. 2.071) and SNAP III. The major differences between SNAP II and SNAP III are problem size, although SNAP III has some additional options. SNAP II requires less memory to run and runs more quickly than SNAP III for smaller problems. This manual covers both versions. Where SNAP II and SNAP III have different capabilities the capabilities of SNAP III will either be shown in [] or be specifically described where it is a separate option.

SNAP can simulate harvests for up to 30 [50] time periods considering harvesting costs, revenues, several species, alternative destinations, non-adjacency requirements, and transportation systems. SNAP attempts to either maximize present net worth or minimize discounted costs.

SNAP combines pattern generation and network analysis to find feasible solutions-- both of units that are selected for harvest and those that are not selected for harvest. SNAP can be used to model various forms of even-aged and uneven-aged management.

In addition to normal non-adjacency rules, SNAP can aggregate units during pattern generation to form "super-polygons" subject to maximum size of opening limitations. Also, SNAP allows specification of up to five sets of control polygons which must not be harvested. Within each control set, SNAP during analysis will connect control polygons with other polygons of eligible seral stages to form connections which cannot be harvested over the planning horizon. The criteria for these connections can be either to minimize discounted value loss or to minimize loss by a user-specified criteria.

MEASUREMENT SYSTEM

Both English and Metric options are available. To select the appropriate system, press "U" while you are in the Main SNAP Editor Menu or in the Main Report Writer Menu. SNAP will display the current measurement system in the upper right corner of the menu.

HARDWARE REQUIREMENTS

SNAP II is designed for 386 and higher microcomputers using DOS. The computer must have an INTEL compatible math coprocessor, 4 megabytes of RAM, an EGA or VGA color monitor and a mouse. The 386 can handle problems up to about 1000 polygons (units) and 3000 road segments (links). SNAP II may need 8 megabytes of RAM for larger problems. SNAP III is designed for Pentium computers, preferably with 32 megabytes of RAM. SNAP III can handle up to 5000 polygons and 10,000 road segments. See Chapter 8 for additional details of memory management.

ORGANIZATION OF THE USER'S GUIDE

This User's Guide does not assume that you are a computer programmer, but it does assume that you know something about harvest scheduling and transportation planning. Parts of the guide that you will probably use frequently are the sections on MENUS and REPORTS. Examples of all menus and reports for SNAP are in this guide along with screen column and row definitions. An INDEX has been included to help you find information. It is a good idea to thumb through Chapter 3 page by page before starting the computer so you can get an idea of where you are going. The menus have been arranged in the order that you will progress through a problem. An example data set has been included on your disk. If you are not familiar with DOS it might be a good idea to review Chapter 6, DIRECTORIES.

INSTALLING SNAP

In order to install the SNAP program on your hard disk, you need the SNAP distribution disk. This disk contains the program and example data sets. Once you have this disk in hand, log onto the A: or B: depending on the disk type. To install the program from the A: drive to the C:\SNAP directory, you type INSTALL A: C:\SNAP [and then enter]. You need to be currently logged onto the A: drive to start the installation process.

TO RUN SNAP

To start the program, change the current directory to C:\SNAP and type GO at the DOS prompt. The SNAP main menu will appear if all is set up correctly, otherwise follow the instructions that the computer gives you to complete the SNAP installation.

SNAP may not like Microsoft WINDOWS or other resident software. The best way to find out is to try it. If you have problems, remove the other software until SNAP works. If you have memory problems when trying to run SNAP see Memory Management, Chapter 8.

Although the GO command is the most common method of starting SNAP, other run options are:

MOUSE OPERATIONS

SNAP text editors can be optionally operated with a mouse. All of the graphic editors require a mouse. SNAP almost exclusively uses the left key or button on the mouse pad. The only exceptions are to select a group of polygons in the Attribute and Habitat Connection Editors and to rotate the view in the Perspective View option of the reports. If you are in doubt, try the left button first.

SNAP DATA

SNAP accepts data through the Forest Service LT-Plus program, the Washington DNR ArcInfo transfer program or any other source that supplies data in the format outlined in Chapter 7.

DOS SHELL

SNAP III can shell to DOS by pressing Alt S at the Main Menu or within any SNAP editor.