CHAPTER TWO - SNAP FILES

SNAP FILE FLOW

To run the SNAP program you must complete five steps.

(1) Build file of the PROJECT filenames.

(2) Prepare the SALE file.

(3) Prepare the LINK file.

(4) Prepare SETUP editors.

(5) Execute PROJECT ANALYSIS

The purpose of each step is briefly described below:

Build file of PROJECT filenames

This file contains the names of all data files the SNAP program requires in order to execute PROJECT ANALYSIS and their location (i.e. the drive and directory path) for SNAP to find them. The purpose of creating the PROJECT filenames is to permit SNAP to automatically call any of 34 types of data files as you move through the data editors and to permit automatic updating of files as you leave data editors. SNAP will also use the PROJECT filenames at PROJECT ANALYSIS time and to generate reports.

Prepare SALE FILE

This step permits the specification of timber harvest files, identification of timber entry points into the network, specification of any special scheduling requirements for individual polygons, silvicultural treatment options, definition of growth and seral stage, and silvicultural prescription matrix.

Prepare LINK FILE

This step is used to define the construction costs for alternative terrain types, specify maintenance costs for road types, convert road log data into network links with calculations of construction, maintenance, and haul costs.

Prepare SETUP EDITORS

This step is used to enter information into a variety of editors describing objectives and constraints for the analysis including: specification of timber destinations, volume requirements by period, habitat connection requirements, goals involving some combination of seral stages, silvicultural treatments and polygon attributes, adjacency controls, and the number of patterns for analysis.

Execute PROJECT ANALYSIS

This step carries out the analysis, generates reports, and displays the reports in tabular or graphic output to the monitor, printer or plotter.

SNAP FILE TYPES

SNAP files are recognized by their extensions which are automatically appended by SNAP when the files are created. As we often refer to the various files by their extensions a brief summary of the file extensions is presented.

The first seven types refer to the base resource and network data that is created outside of SNAP. The first three files are polygon data, the next two are road network data, and the next two are stream network data.

.UA

Contains attribute data for the units in a sequential ASCII file. It is created outside of SNAP.

.US

Contains stick data for the polygons in a sequential ASCII file. It is created outside of SNAP.

.UP

Contains digitized point data for the polygons in a sequential ASCII file. It is created outside of SNAP.

.LA

Contains road network link attribute data. It is a sequential ASCII file created outside of SNAP.

.LP

Contains digitized road network point data. It is a sequential ASCII file created outside of SNAP.

.SA

Contains stream network attribute data. It is a sequential ASCII created outside of SNAP.

.SP

Contains digitized stream network point data. It is a sequential ASCII file created outside of SNAP.

.USD

Contains digitized stick and attribute data for the polygons in a random access binary file. It is created inside SNAP using data from the .UA and .US files.

.UPD

Contains digitized point data in a random access binary file. It is created inside SNAP using data from the .UP file.

.LSD

Contains digitized road network stick and link attribute data. It is a random access binary file created in SNAP from the .LA and .LP files.

.LPD

Contains digitized road network point data. It is a random access binary file created inside of SNAP using data from the .LP file.

.SSD

Contains digitized stream network stick and attribute data. It is a random access binary file created in SNAP from the .SA and .SP files.

.SPD

Contains digitized road network point data. It is a random access binary file created inside of SNAP using data from the .SP file.

.DEF

Contains definitions for seral stages, unit attributes and silvicultural treatments.

.ATT

Contains list of units by attributes.

.SYS

Contains information describing the harvest systems.

.SAF

Contains the final sale information required for analysis.

.GRO

Contains the growth information by silvicultural treatment and seral stage.

.PRI

Contains the silvicultural prescription matrix which controls re-entry time, and re-entry treatment based upon current treatment and seral stage

.TEM

Contains the road templates and cost information required for road construction cost estimation.

.MCD

Contains the information of maintenance costs by road type.

.RLF

Contains the road log file which is developed from the link stick data.

.LIF

Contains the final link file including two way links, variable costs and fixed costs.

.MIL

Contains the mill names, mill nodes and prices by species.

.GRP

Contains the definitions for groups of attributes, seral stages, or silvicultural prescriptions for use in formulating goals.

.SER

Contains your specifications of seral stage and attribute goals.

.TRT

Contains your specifications of silvicultural treatment and attribute goals.

.ADJ

Contains the size of opening limits by attribute and seral stage.

.TIE

Contains the ties between attribute values used to determine the most restrictive opening size.

.COR

Contains the graphic and tabular data to identify critical habitat polygons which must remain connected.

.STG

Contains the identification of the seral stages eligible for each habitat connection.

.VAL

Contains the optional user defined values for rating polygons eligible for each type of habitat connection.

.COV

Contains the seral stage definitions for eligible cover and forage for identifying habitat effectiveness.

.BAN

Contains the definitions of the number of bands, band width, and band weights for evaluating habitat effectiveness.

.GST

Contains the description of volume objectives, period length, discount rate, number of solutions, and type of adjacency control.

OUTPUT.

This is not a file, but is a directory where the reports generated during analysis will be stored.

.RST

This is the extension for an optional ASCII file, SERAL.RST which is used to specify how a stand will be restarted after 100 percent of the volume has been removed as a function of its seral stage. If used, it should be placed in the SNAP subdirectory.

.HT

This is the extension for an optional ASCII file, SERAL.HT which is used to specify tree height and shade density by seral stage for use in stream temperature calculations. If used, it should be placed in the SNAP subdirectory.

.AKA

This is the extension for an optional ASCII file which is used to specify the acres by volume class for a proportionality constraint option used by USDA Forest Service Region 10. If used, it should be placed in the data directory for the project and have the same name project name as the sale file, i.e., GRID10.AKA.