Multispectral Product Operations
On this page, you will find general help for the ProRaster product family including links to documentation, instructional videos, and training videos.
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The ProRaster User Guide is available for download as a PDF.
To any product operation, you connect a new operation that acquires data from the parent operation as input and generates a new output. The type of the parent operation may restrict the number or kind of child operations that can be connected.
A mask operation applies a raster mask that will make any cells in the input raster invalid where the input raster mask is invalid. Typically, you will choose to mask a raster by itself and choose one of the prepared mask bands as the mask. The goal is to remove data from the raster, such as cloud or water, that may compromise analysis or rendering. See the clip raster operation help page.
Both the input raster filename and the output raster filename are fixed and not editable. The system will define these parameters. All you need to do is to specify the masking raster, field, and band. Usually, this mask raster will be the input raster.
Clip to Polygon
A clip to polygon operation clips the input raster to a complex polygon set. The polygon set can contain multiple polygons with holes and islands. The goal is to restrict analysis or rendering to only that specific area that you wish to study. See the clip to polygon operation help page.
Both the input raster filename and the output raster filename are fixed and not editable. The system will define these parameters. All you need to do is to specify the polygon to which the raster will be clipped. You can select from a list of recently accessed polygon files, or browse to a new file. The polygon file must be in a MapInfo Pro TABLE format.
The reproject operation can change the coordinate system of a raster, as well as change the cell size and realign the cell boundaries of a raster. When you work with individual scenes, the coordinate system will usually be appropriate for analysis and rendering. But when you work with mosaics, you may need to select an appropriate coordinate system. See the reproject operation help page.
Both the input raster filename and the output raster filename are fixed and not editable. The system will define these parameters. The current coordinate system is shown, and you can select a new coordinate system from a list of recently used coordinate systems, or by opening the projection explorer dialog.
When you change the coordinate system you should also consider changing the cell size to values that are equivalent in the horizontal units of the new coordinate system. For example, if the raster was 30 meter resolution and the new coordinate system is geographic, then change the cell size to one arc second (1/3600 of a degree).
You can also change the cell alignment. This is less critical. Regardless of what number you choose, you will only ever be able to shift the edges of the cells by up to half a cell width.
The render algorithm operation simply generates a spectral rendering algorithm for the input product. You can select the spectral target, the RGB band combination, and the pan sharpening and masking properties. The output of the operation is an MRD algorithm file, which you can then display and edit in the ProRaster main interface. See the rendering scene help page.
You can use these rendering algorithms as input to image sequences, see the image sequence operation help page.
The Index operation will use a calculator operation to compute a spectral index from one or more spectral bands. For your convenience, scores of spectral index formulas are available for you to choose from, and ProRaster Scientific will automatically match the required spectral inputs to the spectral bands present in your product.
Both the input raster filename and the output raster filename are fixed and not editable. The system will define these parameters.
You need to choose the spectral target. By default, ProRaster chooses the highest value spectral target.
You can apply some conditioning to the spectral band data prior to consuming it in the index formula. The “Scale” option allows you to divide by a scaling factor, usually to convert the values to numbers between 0 and 1. The “Harmonise” option will clamp all input values to within 0 and 1 (meaning values <0 will be set to 0 and values >1 will be set to 1).
Finally, select the index, or the group of indices, that you wish to compute. There are a broad range of index formulas, grouped by their application. Most of these formulas have been acquired from the IDB Index Database (https://www.indexdatabase.de/). Others, where indicated, have been acquired from the ENVI online documentation. Many of these are duplicates. Click on the index in the tree to see its name, description, and formula.
There is no immediate penalty for computing multiple indices, rather than just one. For example, if you are looking for an Index that accurately maps a fire scar, you can select all the Fire and Burn related indices and then display them in ProRaster and make a visual comparison. By doing so, you may discover that one index works better for your study area than the others. Thereafter you can focus on that index. The penalty for choosing many indices only comes at the end of the processing chain when you compute statistics or export the raster. At this point, the system must do all the work to evaluate all the indices.
The Difference operation will use a calculator operation to compute the difference between events in a raster.
Both the input raster filename and the output raster filename are fixed and not editable. The system will define these parameters. The input raster must contain two or more temporal events (a sequence) and the output raster will contain either the same number of events, or one less.
You can compute the difference for all fields and bands in the input raster, or for a selected field and all bands in that field. The operation will only process fields that are Continuous. Image, Image Palette, and Classified fields will not be processed.
You can compute a moving difference, which is the difference between each event and the preceding event. The first event generated in the output raster will correspond to the second event in the input raster.
You can compute a fixed difference, which is the difference between each event and a key event that you select. Usually, the key event will be the first event in the sequence.
The difference operation is executed by calculator operations defined in the output virtual raster. You can edit the calculator expression if you wish. The standard expression is –
“Event – KeyEvent”
In this expression, “Event” and “KeyEvent” are variables that refer to the current event and the key event (or preceding event). These variable names cannot be changed, but you can change the expression. For example, you can reverse the sign of the difference by using –
“KeyEvent – Event”
You can compute the absolute value using –
“abs(Event – KeyEvent)”
You can introduce a conditional expression to output only differential values of interest – for example this expression only outputs difference values that are greater than 0.1 –
The calculator operation can be used to define an index formula manually or modify the output of an index operation, or for many other purposes. For example, the output of many index computations will generally be between -1 and 1, but some pixels may exceed this range. You can use commands like unit(x), clamp(x,from,to), or clip(x,from,to) to improve the data prior to computing statistics.
The output raster filename is fixed and not editable. The system will define this parameter. Alias codes are automatically created for all the fields and bands of the input raster. You can add other rasters and raster sources to this and define additional alias codes if you want to incorporate data from other rasters in the calculation.
Your main task is to create or edit the calculator expression, which acts on raster variables (alias codes) to produce a single-banded output.
Computing statistics is generally the crux of your analysis operation chain. No raster is output from this operation, so it represents the end of the processing chain. The operation outputs the statistics to a binary STTX file that you will not use directly. It also outputs a detailed and readable report to a text file that you can browse. Finally, it outputs key statistics to a comma-delimited text file which you can use as input to graphing applications like Microsoft Excel or use as input for further analysis in platforms like Python.
Both the input raster filename and the output statistics filename are fixed and not editable. The system will define these parameters.
All you need to do is to select the field to process, or the specific field and band. Usually, you will compute statistics for each event in the raster if multiple events are present. You can specify the resolution level to target (0 is the base resolution). It may be advantageous to target a higher resolution initially to test the operation, but generally, you will compute statistics at the base resolution.
When you hit OK on the statistics dialog, a progress dialog will open showing the progress of the operation as it computes statistics. Remember, that this operation forces the entire virtual raster operation chain to be evaluated and draws data from all the way back to the original scene raster files. This is where your computer needs to do some real work!
If you plan to take the raster output products of your analysis into other software packages then you will need to export the MVR files generated in the product operations to a transportable raster format like GeoTIFF.
The Export operation writes a copy of a raster to a new raster file (or files) in a designated raster format. It is primarily designed to convert (or crystallise) an MVR virtual raster into a raster file.
You may want to export data so that it can be viewed or consumed in another software package, or by another user. Another application is to improve rendering performance of an MVR by converting it to an MRR.
For additional information, see the export operation help page.