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MERISVIEW |
How do I start MERISVIEW? [FAQ]
Please refer to this page for this question.
What is the difference between MERISVIEW and ENVIVIEW? [FAQ]
ENVIVIEW is an ENVISAT general purpose tool whereas MERISVIEW is a MERIS general purpose tool and MERISVIEW is much more dedicated to analysis, whereas ENVIVIEW is more dedicated to input/output and display purposes. In addition, since MERISVIEW is only dedicated to MERIS data, it can download data from virtually any MERIS file (including intermediate files) whereas ENVIVIEW can only download data from product files.
What are the fields that I may retrieve? [FAQ]
You may retrieve fields from any file produced with the Level 2 processing, i.e. any Level 2 product or Level 2 intermediate or breakpoint file. In addition to these you may retrieve any field from a Level 1 product file and from the Level 1 intermediate file that follows the rwmap format (i.e. tmp_rad1.meg).
Is it possible to retrieve the annotations from a MERIS product?
Annotations fields are considered like any other product field and are thus listed together with the other products; therefore, to download an annotation you just need to follow the same procedure as when downloading any regular product - of course, in the background, the annotations are bi-linearly interpolated on all pixels.
Can I mask my image? if so, can I use several flags to build up a combination of flags to mask my image? [FAQ]
Yes you may mask your image and you may combine any product flag and/or intermediate flag to do so - you may find the procedure in this page.
How do I load a field from a MERIS product file? [FAQ]
Please refer to this page for this question.
Can I load fields from multiple files? [FAQ]
You may very well load fields from multiple files of various types (L1 or L2 product file, intermediate and breakpoint files) - you will just need to follow the procedure that is explained in this page for each different file.
Is it possible to load the same field from different files (for example the Chlorophyll field from different scenes above the same area)?
For the time being this is not feasible; if you try to do so, a warning message will tell you that you have already loaded a field with the same name and your request will be therefore ignored.
In the case of a very large image, is it possible to extract only a sub part of it? [FAQ]
This feature is currently in development.
How do I mask an image retrieved from a MERIS product file using flags contained in a MERIS intermediate file? [FAQ]
To do so you will have to first download your field from the MERIS product file and then download the flags from the intermediate file - once you have displayed the field you will just need to mask it with the flags of the intermediate file that are now available.
How do I add a colorbar to my image? [FAQ]
Please refer to this page for this question.
How do I add a title to my image? [FAQ]
Please refer to this page for this question.
How may I perform statistics? [FAQ]
You may perform statistics on the entire image; to chose the type of statistical analysis you wish, select the proper one in the preferences window, and to apply it click on the statistics button of the main window - to remove the statistics pannel simply click again on this button.
How can I mask pixels that have values greater or lower than a threshold that I want to set? [FAQ]
Whenever you decide to display a new field, the smallest and greatest values of the image are found and appear on the side of the two sliders that are located just above your main image window. No threshold is used for the display and therefore all values are taken into account. To mask any pixel that has a value greater or smaller than a threshold, you would either need to move the sliders with the mouse or change by hand, using the keyboard, the values given above the slider. The slider located on the right side gives you the value above which any pixel should be masked, and the slider located on the left side gives you the value below which the pixel should be masked.
How can I retrieve data from a previous MERISVIEW session? [FAQ]
You may retrieve the fields from a previous session as long as they have been saved into a *.SAV file. If so, select this file by selecting the retrieve button in the General pull-down menu and all fields of this file will be retrieved. To save the fields that you have downloaded in your session you will have to select the save button instead.
How can I retrieve/save data from/to a HDF or NetCDF file? [FAQ]
This feature is currently in development.
How do I change the colorbar? [FAQ]
To change the colorbar you will need to change your preferences.
How can I perform a map projection of my MERIS image? [FAQ]
Yes, you may project a MERIS image on a map, just click on the map button in the main window. You may select the map projection in the Preferences window.
Can I load multiple fields in one session? if so, how can I specify the field that I want to display? [FAQ]
You may very well load several fields during the same session, these fields may also have been extracted from files of different types (intermediate L2, L1 or L2 products or rwmap L1 files). You chose the field you wish to display by selecting it on the right side of the Current Field button in the main menu :
Can I print my image directly to the printer? [FAQ]
Select General > print to chose the hardcopy printer you want. All active pannels of your main window will be printed as they appear on your display.
Can I save my image into a file? [FAQ]
Select General > print to chose the file format you want. All active pannels of your main window will be printed in your output file as they appear on your display.
Can I modify the label color and font size? [FAQ]
Yes, this may be done in the preferences window.
Can I zoom on my image? [FAQ]
Please refer to this page for this question.
I have already loaded a number of fields but some of them are now irrelevant and I would like to suppress them to release memory and load some new fields, is it possible? [FAQ]
Yes, for this purpose you have two buttons in the main window, they respectively allow you to remove the current field or all the fields of your current selection - once you have removed those fields, the memory that had been allocated for them will be available to load some new fields (... but the memory is still kept by IDL and is not released and not available for any other application).
Is there a maximum number of fields that I can load under MERISVIEW? [FAQ]
There is no hard coded limit for the number of fields you may load, the only restriction is the memory size of your computer.
What kind of stastistical analysis can I perform? [FAQ]
At this present time, from the preferences window, you may chose between four different statistical analyses :
• plain histogram;
• cumulative ascending histogram (% of pixels that have a value smaller than a given threshold);
• cumulative descending histogram (% of pixels that have a value greater than a given threshold);
• line by line percentage of masked pixels.
Can I use MERISVIEW on any platform? [FAQ]
MERISVIEW has been completely developed in IDL except for the MERIS file extractions which interfaces with some C-code that has been developed under SUN workstation. Therefore, until further notice, it is highly recommended to use this software only with SUN workstations. The easiest key to full portability would be to translate the MERIS files into NetCDF or HDF formats to take advantage of the ability of MERISVIEW to handle those formats.