[visad] Strange rendering depending on axis range

Dear VisAD developers,

We are using VisAD for the visualization of mass spectrometry data as part of 
the MZmine 2 framework (http://mzmine.sourceforge.net/).

I found that sometimes the visualization is affected by the range of the axes. 
When visualizing a narrow range of data, the plot shows some strange artefacts 
such as lines.  After a bit of debugging, I managed to write a short Java 
program that demonstrates the issue (attached as VisadTest.java)

The program creates a simple Linear2DSet of 1000 x 1000 dimension. The Z values 
are set to zero for the whole domain, therefore the visualization only shows a 
flat plane. The strange thing is that depending on the range of the X axis, the 
visualization is different (note that the resolution of the Linear2DSet stays 
constant).

The range of the X axis is defined in the program here:
        double xMin = 100;
        double xMax = 100.007;

I have attached screenshots demonstrating the VisAD behavior as I change the 
range of the X axis from 100-100.5 to 100-100.0005. Finer ranges show some 
strange patterns instead of solid color. Is this behavior normal? I believe the 
visualization should be exactly the same except the X axis label. Is this a bug 
of VisAD?

Best regards,

Tomas

PS: I am using the latest VisAD (Thu Mar 22 13:01:31 CDT 2012  Rev:5952), 
running Java 1.6.0_31 on Mac OS X 10.7.4.


===============================================
Tomáš Pluskal
G0 Cell Unit, Okinawa Institute of Science and Technology Graduate University
1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan
TEL: +81-98-966-8684
Fax: +81-98-966-2890

Attachment: VisadTest.java
Description: VisadTest.java

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