HDF/netCDF Browser
Table of Contents
- Introduction
- Instructions
The HDF/netCDF browser is a powerful tool for viewing HDF and netCDF
files and selecting data from them for further processing.
HDF and netCDF
are two similar common file formats used for data in the form of
arrays and grids, especially in the earth sciences such as Meteorology and Oceanography.
The term variable/SDS is used below. This means
variable for netCDF and
SDS for HDF.
The HDF/netCDF browser is defined by the file hdf.tcl.
- Use the
choose_file
GUI to open an input file.
Instructions can be displayed by pressing this GUI's own help button.
Opening the file should result in the display of a file structure tree.
- Use this tree as follows to select either a variable/SDS or an attribute.
(The default selection is a variable/SDS with the maximum number of elements.)
- Click on a variable/SDS to select it and display the spatial sampling widget.
- Click on a '
+' to display attribute names.
- Click on an attribute select it and display its value.
- The spatial sampling widget allows you to select part of a variable/SDS.
(The entire variable/SDS is selected by default.)
Each dimension is represented by a row containing one or two lines.
The first line represents subscript values.
If a coordinate variable exists then it is represented on a second line.
Change a subscript using any of the following:
- Drag the slider along the scale widget.
This is convenient for coarse adjustment.
- Click on the spinbox arrows or scale troughs.
- Press the keyboard up/down keys.
- Use the keyboard to enter numbers.
Fractional subscript values can be used to produce magnification.
- On an image, drag the mouse to define a bounding box.
- Press the
Dimension button to restore all defaults.
- Press the
From, To or Step
column heading button to restore defaults in a column.
- Press the row heading buttons to toggle a row between defaults
and saved values.
The values selected along a dimension are defined as follows:
- If step > 0 then from, to
and step define an arithmetic progression.
- If step = 0 and expression is blank then use single
value from.
- If step = 0 and expression is not blank then use this expression.
- The following buttons along the bottom are used to select an action:
Range:
Display minimum and maximum value.
Text:
Display start of data as text.
Graph:
Display data as XY graph(s).
Image:
Display data as image(s).
Animate:
Animate window-sequence produced by Graph or Image.
NAO:
Create Numeric Array Object.
Re-read:
Force a read (e.g. after rewriting the file).
Select Raw mode if you want the following attributes to be ignored:
scale_factor, add_offset, valid_min, valid_max, valid_range.