The simplest way to set a file parameter is to type its value straight into the entry box beside its caption in the file parameter dialogue. For single values, this is the only way to enter them initially. The tick button replaces the currently saved value with what has been typed in, while the cross button reverts the entry field to the saved value.

The datatype (e.g., INTEGER or REAL) is displayed by hovering over the caption to the left. This will also display any comment associated with the parameter. If multiple values are required, the dimensions will also be displayed at this point, e.g., 3 x 3 of REAL). If there are multiple values, you get the pencil icon to the right of the entry field, which normally you would use to load them from a file. However, you can choose to type them in.

In Simile v7, arrays and lists are entered in the JSON format. In this format, an array is an ordered list of its members, separated by commas, enclosed in square brackets. Thus a 5-element array of real could be [2.5,3.5,1.5,2.5,3.5], while a 3x3-element array of integer might be: [[5,10,15],[6,7,9],[4,1,8]]. A list is a list of pairs of index and value, with a colon between the index and value, and the pairs separated by commas, enclosed in curly brackets. Thus a time series with integer values applying at times 10, 50 and 100 could be written: {10:33, 50:45, 100:78}. An array can also be written as a list, with the integers from 1 to its size as the indices. The index-value pairs in a list do not need to be in any particular order. The older format described below also works, for the sake of backward compatibility.

In earlier versions, when typing in multiple values, you must alternate between indices and values at each level, and group sub-arrays in curly brackets. So for instance a five-element array of real could be: 1 2.5 2 3.5 3 1.5 4 2.5 5 3.5, while a 3x3-element array of integer might be: 1 {1 5 2 10 3 15} 2 {1 6 2 7 3 9} 3 {1 4 2 1 3 8}.

If redisplaying the file parameter dialogue in an earlier version, the values will be shown with hashes and colons around the indices, to make the data more readable. For instance the five-element array above would look like this: #1: 2.5 #2: 3.5 #3: 1.5 #4: 2.5 #5: 3.5. You must keep these if editing the entry field to change the value, but at this point you can also go to the table data dialogue and edit the values in a version of the table helper. If the values have previously been loaded from a datafile and there are very many of them, the entry field will be greyed out so you cannot type into it, and will also contain an ellipsis rather than listing all the values. In this case they can only be changed via the table entry dialogue.

In: Contents >> Working with external data >> The file parameter dialogue

The File Parameters dialogue will contain entry fields for both fixed and variable parameters. Fixed parameters must be given a value; their captions in the dialogue will be shown in red until a correctly formatted value has been supplied. Variable parameters do not need a value, and can be left empty, so the value can be set by a slider while running the model. However, it is possible to enter a time series in the File Parameters dialogue, which will cause the variable parameter's value to be set at a series of specified time points while the model is running. You would normally set up the time series using the table data dialogue, but the direct method is described here to clarify the analogy with setting values for an array.

Entry format

The format for entering a time series is the same as for a one-dimensional array, except time points are given instead of indices. The time points can be REAL values, and do not have to be at regular intervals. Data for time point zero is loaded whenever the model is reset. So, to set a value five times between time 0 and time 100, the entry might look like this: 0 12 20 11 40 8 60 7 80 9

If the value to be set is an array, the data must specify a multi-dimensional array, with the time points as the outermost indices.

Special indices and values

The data for a time series can include various combinations of special index and value, which affect how the numerical data is interpreted:

• Data at time point NOW is loaded into the model as soon as the File Parameters dialogue is closed, and then not used again. Wiggling a slider effectively sets data at time point NOW.
• For time point OTHERS, you do not enter a value; instead, you enter one of the special values use_last, use_closest or interpolate. These select the different methods for getting a value when the time is not exactly equal to one of the indices in the series. use_last specifies the default behaviour; each value stays in the model until the next time point is reached. use_closest causes the value to change midway between the two specified time points, while interpolate means the value changes continuously and linearly between one specified time point and the next.
• The INTERVAL time point allows you to supply a time unit which applies to the other indices. This can be useful if you have files containing time series data with the times specified in different units. For instance, if the supply the following data for a time series: 1 3.2 2 4.5 3 6.3 INTERVAL week ...then unless the time unit for model execution is set to something other than day, the variable will change value at times 7, 14 and 21. The time unit can be anything that Simile understands, e.g., ms.
• There is also another special value, restart, which has a normal numerical time point as its index; this specifies a time at which the model starts reusing values at the beginning of the time series, starting with time 0. The value will then follow a regular pattern, whose period is the time index of the restart value. The time for restart must be the last in the sequence.

Example: rough approximation of sinusoidal variation with period 100 time units:

0 0 12.5 0.7 25 1 37.5 0.7 62.5 -0.7 75 -1 87.5 -0.7 OTHERS interpolate 100 restart

When entering time series values in the table data dialogue, there are special buttons to get these behaviours by setting the special indices and values.

In: Contents >> Working with external data >> The file parameter dialogue

Ther normal way to use the file parameter system is to create and save references to data in other files. To do this, click the 'pencil' icon to the right of the data entry field. This brings up the table data dialogue, which allows you to specify the file containing the data, and how to get the data from the file.

Once this has been done, hovering over the entry field will produce a popup showing which file contains the actual data. Hitting the 'pencil' button again will show the reference information and allow it to be altered.

In: Contents >> Working with external data >> The file parameter dialogue

Once you have specified the data for all the file parameters, you can save that data in a scenario file (extension .spf, sometimes referred to as a parameter metafile). This file does not necessarily contain the actual data, it can contain references to the files that actually contain the data. It is in an XML format, allowing it to be examined and edited if required.

The normal way to save the scenario file is to click the 'diskette' button in the top-right corner of the file parameter dialogue, by the caption TOP LEVEL. This will create a file containing information for all the parameters in the model. You can save a scenario file for just the parameters in a submodel, by clicking on the 'diskette' button to the right of the caption for that submodel. This file will include the information for all submodels under that one in the hierarchy.

When the scenario file is saved, the locations of any data files referred to will be included as relative paths. This means that if you move the scenario file to a new location, for instance when copying the model and its data to another computer, the data files must be in the same location relative to the scenario file (e.g., in the same folder) as they were when it was set up.

To load a scenario file, click the 'open folder' button to the right of the submodel caption. This action will not load the data itself; that only happens when you click the 'tick' beside a parameter's entry field, or hit the 'OK' button at the bottom of the dialogue. If you have made separate scenario files for submodels, it is important that they are loaded into the same submodels for which they were saved, otherwise Simile will not be able to find the file parameter elements that they refer to, since it will be looking in the wrong submodel or at the wrong level. Loading a scenario file overwrites any information that was already present for the parameters mentioned in the file. This allows you to have one set of values for a submodel saved as part of a top-level scenario file, but still load different values just for that submodel from another scenario file.

In: Contents >> Working with external data >> The file parameter dialogue

This is the first tab in the table data dialogue. Use this method if the data for each component is in a single column in a file or database.

To select a file as the source of the data,  hit the "Browse..." button and navigate to it. You can select .csv or Excel-compatible files this way. As of Simile v6.9 you can also load columns from a MySQL database. To to this, hit the "MySQL Connection" button and supply the hostname, username, password and database ID for MySQL.

If using a MySQL database or an ODBC-compatible format of file (e.g., .xls) then once you have browsed to the required file or entered the database access information, you must select the table in which the relevant data appears, using the "Database table or worksheet" pulldown menu. Once the table is selected, the column headers will be loaded into the list box below. If using a .csv file, this is not needed because the whole file is one table. When selecting the file you can also edit the character (comma by default) that separates the columns.

Storing data in a file

In order to be able to access the data, they must be stored in a certain format in the file. The file should be rectangular, consisting of a certain number of rows and a certain number of columns. The number of columns corresponds to the number of variables in the file (or, in database terms, the number of fields for each record). The file has as many records as there are units for which data were recorded, plus a single header record. The format is comma-separated values (CSV) which means that each value is separated by a comma from the preceding value. There is no comma at the end of a record. Most software packages that handle data can create files in this format.

The following is an example of a simple file containing data on the age, height and diameter of five trees:

age, height, diameter

25, 15, 0.31

32, 17, 0.37

16, 10, 0.2

19, 12, 0.23

21, 14, 0.29

Creating a new table

To create a new table using the dialogue involves several steps. The first step is to select the file from which the table data are to be taken. To do this, click the "Browse" button on the dialogue box. The file path name is then displayed in the edit box "Data file".

If you are using a more recent version of Simile (5.4 or later), you can also select a data file in an ODBC-compatible format (eg, .xls) if you have the appropriate drivers loaded on your computer. In this case you also need to select the individual table or worksheet holding your data from a pulldown menu.

After selecting the file and datasheet, the table dialogue reads and displays the column headings in a list box. The column headings are taken from the first row of the file. The rest of the file is not checked, at this stage, for speed.

One (and only one) of these headings is used to designate the data column. Drag this column heading from the list box to the edit box labelled "Use as data column". In the example file shown above, you would have the choice of "age", "height" or "diameter" and could drag any one of these to the data column edit box. The cursor changes shape while you are dragging the heading, to represent the data moving.

If you wish to create one or more indices to the data column, drag the heading corresponding to the desired index into the list box labelled "Use as index". To delete an index, drag the column heading from the "Use as index" list box back into the "Table column headings" list box. It is not always necessary to designate an index. If none is given, the row number is used to access each record. If indices are given, then the array returned will consist of the values from the data column indexed by the value(s) from the index column(s) in the rows where they were found. Simile v6.7p2 introduces a new feature: if one or more index columns are specified, then the single word ,line can be used in place of a data column header, and this means that the data in the array will be the line numbers where each index value or combination of index values were found. For instance if the table at the bottom of this page were loaded with the index column headers Y index and X index (in that order!) and the data column header ,line then the first row of the resulting matrix would have the values 1,4,7, these being the rows where the y index of 1 was found, sorted by X index.

You can view the data you have loaded in a separate window. To do this, click the View/Edit button. You can make changes to the data in this window, and click OK to accept the changes or Cancel to abandon them. You can also save the data to a file. Note that if you extracted the data from a file containing more than one variable, you should not save the extracted data to the same file, or you will lose the other variables.

Editing an existing table

If a table already exists for the component, you will not need to follow the above steps again. If you wish to see or change the data in the table, you can click the View/Edit button. This will present you with the Table Editor, as above. If you wish to extract data from a different file, you can use the Browse button, as above, to begin as if creating a new table. If the data in the file have changed since the table was created, you can use the Load button, to extract the new data using the same specification of column heading and indices. (If the file is not present, perhaps because you are working on a different machine from where the model was created, clicking the load button will give an error.)

Final notes

When preparing to use multiple indices, it is often best to arrange the index columns in the data file in a logical sequence, for example as follows:

X index	Y index	Height	Diameter
1	1	12.3	1.3
1	2	12.7	1.2
1	3	13.1	0.9
2	1	11.8	1.5
2	2	12.3	1.4
2	3	11.7	0.9
3	1	13.5	1.0
3	2	12.1	1.1
3	3	13.0	1.1

For this file, two indices would be selected, the x- and y-values, together with one data column, either the height or the width. If both were needed, it would be necessary to have two variables, and to create a table in each one that each used one of these columns. The indices systematically provide values for a three-by-three grid. This makes it easy to extract the data using the first of the techniques outlined above.

In: Contents >> Working with external data >> The table data dialogue

If you have a .csv file with a 2-dimensional grid of data items, this can be loaded directly into a 2-dimensional array file parameter in Simile. For other 2-D formats that can be read into a spreadsheet, you can create the .csv file.

To use this file, go to the second tab in the table data dialogue. Here, you can browse to the file containing your data. When selecting the file you can also edit the character (comma by default) that separates the columns. Once you have done that, the four entry fields below will be filled, with "Finish at row" and "Finish at column" containing the number of rows and columns respectively in the file.

You can change the values in these fields in order to read only a part of the grid of values. This is most likely to be needed if the file contains headers that are not actually part of the data. For instance if the first row of the file contains headers, you specify "Start at row: 2" to avoid reading these into the table. You can use the View/Edit function to look at the data that will be read, and adjust the start row and column until it shows the data you want. Whatever values these have, the first row and column that is actually read will have index 1 in the data table (or 0 if it is a time series).

As of Simile 5.4 there are some extra features in this pane: the 'transpose' checkbutton causes the outer indices to correspond to the columns, rather than the rows. Also you can reverse the bounds, i.e., put a higher number in the "Start at..." than the "Finish at..." entries. This has the effect that the same part of the file will be read, but in the opposite order; the last row or column will contain the data items for index 1.

As of Simile v5.5 there is also the option to use fields from the grid as indices as well as data. This is analogous to the way index columns can be specified when reading data from columns, and is useful when the indices need to be enumerated type members. Below the entries for the start and finish rows and columns, there are pull-down menus to choose the source of the indices. By default these are set to "Position in data area", which causes the indices to be generated as described above. The row indices can also be got from "First column in grid" (i.e., leftmost column), or "Column to left of data". If either of these are selected, the index for each row will be the item in that row and the specified column. Note that you cannot choose these options if the data area starts at column 1, and if it starts at column 2 then they both do the same thing, i.e., get the index item from column 1. There are a similar set of options for getting the column indices from a row outside the data area.

In: Contents >> Working with external data >> The table data dialogue

 

Simile can extract a 2-dimensional array of data from an image file, with each pixel in the image corresponding to a datapoint. The image can be in any format supported by the Tkimg package, which is to say, most of them.

To get image data, use the third tab in the table data dialogue. The upper panel on this tab is much the same as on the data in grid tab, and does much the same thing; you browse to the file, and select the positions in the image at which to start and finish reading data if you do not want the whole thing.As in the case of a data grid, you can reverse each axis or transpose the axes.

The unique bit is the bottom panel, Values for Colours, by which you can instruct how each colour in the image is to be converted into a value in the data array. "Value for black" and "Value for white" specify the endpoints of the range of values. For other colours, in general the lighter it is, the further from "black" and the closer to "white" the corresponding value will be. There is a pulldown menu with a choice of methods for getting values from other colours; "use luminosity" averages the intensity of red, green and blue, or you can use any of these levels on their own. For instance, an area of pure magenta will give the same value as white if using red or blue levels, and the same value as black if using green level. If using luminosity the value for magenta will be (2*white+black)/3. You can also select "use 8-bit colourmap" which just assigns a unique value to each colour in an 8-bit coloured image, the intention being that these same values are also available to set the colour legend in the grid helper, allowing a version of the image to be reproduced.

Finally there is a field to enter a value which will be used where the image is transparent (clear). You only need to enter a value here if your image has some transparent areas. This value can be outside the range from black to white.

In: Contents >> Working with external data >> The table data dialogue

GeoTIFF is a file format which is based on the TIFF image, but which is not actually an image and cannot be displayed in most image viewers. It differs from an image file in that:

• It also contains georeferencing data, and
• The image data can be in a number of formats including floating-point.

Simile uses GDAL (Georeferencing Data Abstraction Library) to read GeoTIFFs and other similar data files and convert them into 2-D arrays of parameter values. This library is not distributed with Simile, but it is Free Software; you must go and find it on the Web, and install it on your computer before you can use this feature of Simile. A version of GDAL is included in most Linux distributions and can be installed via the package manager. When it is installed, Simile can also create GeoTIFFs using the grid helper.

Havng done this, the procedure for reading data from a GeoTIFF is much the same as for a grid of values in a .csv file. The actual values in the file are used in the data array without any conversion; the assumption being that since they can be floating-point, whoever created the dataset would have been able to include physically meaningful values.

Because getting data from this type of file is a low-level operation, it is much faster than the other options for loading data from files where very large arrays are involved. However the price for this is the loss of the "transpose" and reverse ordering options.

In: Contents >> Working with external data >> The table data dialogue

Once you are in the table data dialogue, you can hit the View/Edit button to bring up a version of the table helper to display your data and, if necessary, edit it. The data need not have come from a file; it might just have been typed into the entry field of the file parameters dialogue. However it will not work if the data has been loaded as raw data from the scenario file.

This tool has all the features of the table helper, i.e., you can arrange the different index and time point headings vertically or horizontally, and you can save the displayed data as a .csv file. It also allows you to edit the data, either by typing values into individual fields or by cutting and pasting a grid of values into the grid. For example, a quick way to transpose a square array: Put outer indices on rows and inner ones on columns, then cut all the data, then put inner indices on rows and outer ones on columns and paste it back in.

The main use of this tool though is to check after reading data from a file, using whatever method, that you have actually picked up the data you intended to get.

In: Contents >> Working with external data >> The table data dialogue

In the section on time series formats, we saw that the series includes special time points and special values to specify what what values to use away from the actual data points. If you are using one of the mechanisms provided by the table data dialogue to get your data, you do not have the opportunity to include these special points (unless they happen to be in your .csv file, and if they are, they work fine). But you can get the same effect by including them with the tools in the 'other times' panel in the top right corner. These are only available if providing values for a variable parameter when running the model. 

The pulldown menu for "Between points" allows you to select from three options which have the same effect as the special values for the time point OTHERS: "use_last", "use_closest" and "interpolate". The entry for "Wraparound at" has the same effect as the time point given for the special value "restart".

There is also an entry field to set the units for your time series indices as described for the INTERVAL point.

In: Help >> Working with external data >> The Table Data dialogue

Normally, the scenario file contains only references to data files, with information as to how the data is to be extracted. However, if you type the data straight into the entry field in the file parameter dialogue, or edit it with the table editor from the table data dialogue, the resulting data no longer corresponds to anything that can be got from a data file, so instead the data is stored directly in the scenario file. This is usually a bad thing, because the XML format used is unwieldy and verbose, and it may take a long time to load or save. But keeping references in the scenario file also has disadvantages, chiefly:

1. When publishing a model with a scenario file like this, the file itself must be included along with all the other files referenced by it, and these must be installed in the same place in the directory tree relative to the scenario file as they were when the scenario was created

2. The process of loading values from a .csv file is quite time consuming, as the file has to be parsed and checked for syntax errors before the ASCII numerals can be converted into their actual values, and this has to be done every time the data is loaded.

So we came up with a way to maximize convenience, and added a checkbox to the table data dialogue captioned "Include values in scenario files". If you check this, then when you save a scenario file including the parameter in question, it will include all the data for that parameter even if it is also available in the datafile. Furthermore, instead of it all being in longhand XML, it will be in raw binary format, base64-encoded into Ascii and stuffed into a CDATA field.

This means it is small. And fast. If the model uses a lot of data that isn't going to change from one scenario to the next, this is the best way of handling it. There is a slight downside; the values are unpacked and loaded directly into the model's data structures, and are never converted into the TclTk format that allows them to be displayed as text (except for a few at the start and end, to display in the file parameter dialogue, and these give you just the raw numbers if using booleans or enumerated types). So you cannot look at them or change them with the table editor -- but that gets a bit difficult with very large arrays anyway. The only way to change them is to load them once more from a datafile.

In: Contents >> Working with external data >> The table data dialogue

 

 

 

Case 6: providing values for 2-dimensional variables

A variable will need a 2-dimensional array of parameter values if it is itself a 2-dimensional array variable, or if it is inside a 2-dimensional multiple-instance submodel, or if it is a 1-dimensional array variable inside an ordinary multiple-instance submodel, or if it is inside 2 nested multiple-instance submodels.

There are two ways of providing two-dimensional data for such a variable. The first two are generalizations of methods already described, and can also be used for higher-dimensional variables. The third involves reading data directly from a file in a 2-dimensional format, and was introduced in Simile v4.8.

Values direct from scenario file

This method is limited to small arrays. You enter the data in the edit field in the file parameter value as for one-dimensional arrays, but in place of each value there is another list of index and value pairs, in curly brackets. For instance, the data for a 4x3 array of integers could be supplied as:

1 {1 4 2 9 3 1} 2 {1 8 2 5 3 6} 3 {1 9 2 11 3 6} 4 {1 0 2 7 3 9}

Note that after these values are accepted by the dialogue, it will show the indices with a hash and colon, e.g., #2: to distinguish them from the data items. They can in fact be entered either with or without these decorations, making it easier to enter them by cutting and pasting.

It is fairly easy to see how this mechanism can be extended to cope with higher-dimensional arrays.

Values from a column in a .csv (comma-separated value) file

The data file should be in standard csv (comma-separated value) format. It should have one header line, consisting of one or more labels, separated by commas, followed by n lines. Each line should have the same number of values as there are labels in the header line, and again the values should be separated by commas. The number (n) of data lines should be at least as great as the number of instances for the submodel. One column should contain the values required for the variable in the model. There should also be one column containing the outer index values, and one column containing the inner index values.

For instance, a .csv file to generate the same array as in the last subsection, might look like this:

IndH,IndV,Val,

1,1,4,

1,2,8,

1,3,9,

1,4,0,

2,1,9,

2,2,5,

2,3,11,

2,4,7,

3,1,1,

3,2,6,

3,3,6,

3,4,9,

Note that the row index (which would normally correspond to the outer index in a 2-D array within Simile) actually appears after the column index in the file. This does not matter; the columns can be in any order in the file. So can the rows, since their ordering in the model data is going to be specified by the values in the index columns, rather than their line numbers.

When you come to run the model

Simile will produce a File Parameter dialogue window, and this will contain an entry for this variable.

1. Click on the Read table button for this variable

2. Select the 'Data from column' tab in the Table Data dialogue, if it is not already selected

3. Browse through your file system to find the .csv file containing the data values.

4. Click on the OK button.

   You will now see a window listing the columns in the table, by the label associated with each column.

5. Drag the header of the column containing the values for the outermost index across into the 'indices' listbox. In the example above, this column header is IndV.

6. Repeat this action for the inner index. In the example above, this column header is IndH.

7. Double-click on the label corresponding to the column of values you wish to assign to the variable. In the example, it is Val.

8. Click on the OK button.

9. Click Save if you wish to save this setting (along with any others), and specify a file to save it in.

10. Click OK when you wish to proceed with the simulation.

Values from a grid in a .csv file

In many cases, the data for a 2-d array is available as a grid of values in a .csv file, typically one saved by a spreadsheet. In such cases it is difficult to convert it to a single column with separate columns for indices, so Simile allows this type of data to be read directly. The rows in the grid will correspond to the outermost index of the Simile array, and the columns to the innermost index. If the grid data is arranged the other way round from this, the spreadsheet's 'transpose' function can be used to swap the rows and columns.

After you click the 'get values from file' button in the File Parameters dialogue, the Table Data dialogue contains four tabs. Initially, the 'Data in Column' tab is raised, but for this case we use the 'Data in Grid' tab. So first click on that tab to raise it.

Now we see a file selector, the same as in the previous examples. Use it to open your .csv file containing the grid of values.

On opening the file, the four entry fields for start/finish at row/column will be filled with the numbers of the first and last rows and columns respectively, providing indication of the total size of the grid of data in the file. Note that any header rows and/or columns will be included in these dimensions, so the 'start at' values will always be 1. At this point you can adjust the values to correspond to the part of the grid you actually want to load. At any time you can hit the View/Edit button on the right of the dialogue, to display a grid of the values in the part of the file currently selected for loading. Ths is useful if you are unsure which part of the file contains headers and which the numerical values. However, note that the table display tool only works up to a maximum of 10,000 rows or columns.

The size of the area you eventually select must match the dimensions of the array you need to load into the model. These dimensions are displayed in the header of the Table Data dialogue for convenience. Once you have chosen the appropriate start and end points, you can use the View/Edit button again to actually change some of the values (e.g., if some were badly formatted in the file) but be aware that if you do this and then save the scenario, all the values will be saved in the parameter file, rather than just a reference to the .csv file.

Values from an image or other binary-format file

Loading a 2-D array of data from an image is very much like loading it from a grid of numerical values. Follow the same procedure except, when you open the Table Data dialogue, select the 'Data from Image' tab. You then choose the area of the image from which you want to load values, exactly as was done for the case of loading data from a .csv grid, except in this case there are no header rows or columns to worry about.

There is an important extra step when using an image file - each pixel in an image has a colour, and you must specify how these colours are to be converted into numerical values to use in the model. This has to be done before you can use the View/Edit button, since the table will display numerical values. Each pixel will correspond to a number between a lower and an upper bound. These bounds are entered as 'Value for black' and 'Value for white', and these are the values that will be generated for black, and white, pixels respectively. Value for black can be greater than or less than value for white. Pixels of other colours will generate values between these two values, as specified in the 'For other colours' pulldown menu. For instance, if you select 'Use green level', a green pixel will give the same value as a white one, since the green level in white is 100%, while a red pixel will give the same value as a black one, since the red level in green is 0%.

If the image file has 8-bit colourmap data, as is the case for most GIF files, then these values can be used directly, and by setting the values for black and for white to 0 and 255 respectively, the values themselves will be preserved. Finally, some images contain transparent areas; when using such an image you must set a separate value for transparent pixels in the 'Value for clear' entry field. This need not be in the range between the values for black and for white.

Other grid data formats

Several other data file formats, principally GeoTIFFs, can be loaded into Simile model parameters if you have the Geospatial Data Abstraction Library (GDAL) installed on your computer. This library is not included in Simile's installation, but is distributed free of charge, and is available for all operating systems for which Simile is supported. The procedure for loading these data files is the same as for loading image data, except that since the values in the files are already interpreted as numerical rather than colour, there is no need to specify how they are to be converted to numeric values. Use the last tab in the table values dialogue (Data from GeoTIFF, etc).

In: Contents >> Working with external data >> Using scenario files