Tuflow and estry manual Version 3

3.10.1 “MI” Commands

Commands containing “MI” (eg. Read MI Zpts) read and/or write both .mif and .mid files. The geographical location of objects in the GIS layer is important as this controls which part of the model they affect.

When specifying the .mif/.mid file, the extension may be omitted, or either of the .mif or .mid extensions may be used.

Table 4 .6 defines the different MIF data objects supported.

When digitising objects, it is preferable that they do not snap to the 2D cell sides or corners as this may produce indeterminate effects.

3.10.2“MID” Commands

Commands containing “MID” (eg. Read MID Zpts) only read the .mid file. The .mif file is not used. These commands rely on the first two columns of attribute data to define the cell reference (ie. n,m or row,column). Data in subsequent columns depends on the data type. It is not necessary for the user to create these layers manually, as TUFLOW produces them.

Moving an object in a layer that is read by a “MID” command should never occur and has misleading effects.

In earlier TUFLOW versions, only the MID option was available, however, the MID option is now normally only used for Zpts (see Read MID Zpts).

Table 4.6 TUFLOW Interpretation of MIF Objects

Object Type	TUFLOW Interpretation
Point	Refers to the cell that the point falls within. Points snapped to the sides or corners of a 2D cell may give uncertain outcomes as to which cell the point refers to.
Line (straight line)	Affects a continuous line of 2D cells. Cells with their centroid (centre point) closest to the line are selected.
Pline (line with one or more segments)	As for Line above.
Region (polygon)	Either effects any 2D cell, Zpt or other parameter point that falls within the region. A 2D cell is only effected if it’s centroid falls within the region. If the cell centroid or point lies exactly on the perimeter, uncertain outcomes may occur. Holes within a region are accepted. Or, just the centroid is used. Examples are flow constrictions (FC) and time-series output locations (PO).
Ellipse	Ignored (do not use).
Rect (Rectangle)	Ignored (do not use).
Roundrect (Rounded Rectangle)	Ignored (do not use).
Multiple (Combined) Objects	In later versions of TUFLOW, multiple point, polyline and region objects are generally accepted (ERROR or WARNING messages are given if not the case).
Collections	Not supported. Collections are groups of objects of differing type.
Text	Ignored.