McIDAS-V Support Forums

Hi -

I have uploaded the bundle 'noPostProcessing.mcvz' to the SSEC server. This bundle correctly displays an image each from 2 different AHI bands as retrieved from the geoarc server. However, afterwards no ad-hoc post-processing is possible. E.g. when doing a simple image difference McIDAS-V does not go on when hitting the 'OK' after having selected the 2 images. This happens with version 1.5 and with a recent nightly 1.7. Can you replicate this?

HP

Hi HP -

The problem you are seeing is related to Inquiry 2453. We are currently waiting on programmers to evaluate the problem to get an idea of the scope of the work involved in resolving it. This is also an issue with unzipped bundles where originally clicking OK to evaluate a formula doesn't do anything. However, with unzipped bundles you can go to the Advanced tab of the Field Selector and see that McIDAS-V is requesting a size of 0,0 for each of the bands being passed through the formula. With unzipped bundles, you have the ability to modify this 0,0 to other values to get your data to display.

I've made a note in the inquiry to contact you on any updates.

Thanks for reporting this -
Bob Carp

Hi Bob -

Many thanks for (re-)treating this issue. As a temporary measure, I wonder whether one could tweak the bundle xml with a correct size. I have had a brief look into the file, but could not find anything that makes sense for me.

HP

Addendum:
I learn from my EUMETSAT friends that the problem exist only from version 1.5 onward. 1.4 is fine, but does not allow access to AHI data.
HP

Hi HP -

That's good to know that this was not a problem in McV 1.4. I went back and verified that this is true and I added this information to the inquiry. I did a side-by-side diff of the bundle files and there are many differences between a bundle created in McV 1.4 and McV 1.7beta1, but nothing is jumping out at me either as to why things would be working differently in the nightly.

For now, I did find one workaround that may work for you. After loading the bundle in the nightly, you can use the Jython Shell to get a reference to each data object displayed and then you can perform mathematical operations on those data objects. Here is what you can do:

1. Load your bundle as you normally would.
2. Open the Jython Shell and get a reference to the first imagery layer displayed:
   

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   sat_layer_1 = activeDisplay().getLayer(1)
   # getLayer() grabs a reference to a displayed layer.  The number is the index number of the layer
   # in the display which is 0-based.  Layer 0 would be the first layer displayed (likely the map) and 1
   # would be the first real layer of data displayed.  This is going to be the bottom imagery layer in
   # the Legend.  You can verify you got the correct layer by running:
   # sat_layer_1.setLayerVisible(False)
   # You can re-run this with "True" to turn the visibility back on.

3. Now that we have a reference to the layer, we need a reference to the actual data. Run:
   

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   sat_data_1 = sat_layer_1.getData()

4. We also need a reference to the other data object. Run:
   

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   sat_data_2 = activeDisplay().getLayer(2).getData()

5. Now you can subtract the layers with:
   

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   sat_sub = sub(sat_data_1, sat_data_2)

6. Finally, display the subtracted data with:
   

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   sub_layer = activeDisplay().createLayer("Image Display",sat_sub)

If you give this a try and have any problems or thoughts on it, please let me know.

Thanks -
Bob

You are ever so helpful, Bob. Works perfectly. I will now add bells and whistles.
many thanks, HP