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[IDV #LTA-507350]: IDV




On Tue, 22 Mar 2011, Lalitha Venkatramani wrote:

> New Client Reply: IDV
>
> Ok, IDV image looks great. That is the reason I am trying to understand the 
> projection.
>
> As I explained in my email,
> minimum lat is 13.8992
>  maximum lat is 65.3821
>  minimum lon is -144.517
>  maximum lon is  41.9596
>
> Rows, columns, xres and yres ( xres and yres in meters)of the lambert 
> conformal  projection:480 576 10700 10700
> > Resolution in lambert conformal is 10700 meters. When I display using IDV, 
> > I get the image with properties set to 576 X 480 pixels.
>
> If you convert the lambert projection to latlon , FOR THE SAME RESOLUTION 
> 10.7 km, Latitude points are roughly,
>
> Latitude spans 52 degrees
> 1 degree is 100 km. so, roughly 520 points for a 10 km resolution
>
> Latitude spans = 103 degrees roughly - s0, 1030 grid points for a 10 km 
> resolution.
>
> When I convert the original grib file to projections/predefined/world in IDV 
> and display in lat/lon projection.
I see IDV shows 1203 x 918 points and the image looks great.
>
>

I did the same convertion as you, but I am not sure how do you
see how many points in the IDV display. What I did is to export the
display image
to the nc file, and then I can tell the same number of points in both
projection.


Yuan
> You may notice, I use 10 km resolution which is the resolution in the grib 
> file.
>
> So, I am just interested to know if you use the same resolution.
> Can you please tell me how do you convert lambert to world?
>
> I see your source code, but I could not locate that area yet.
>
>
> Thanks a lot,
> Lalitha
>
> -----Original Message-----
> From: Lalitha Venkatramani
> Sent: Tuesday, March 22, 2011 5:51 PM
> To: 'address@hidden'
> Subject: RE: [IDV #LTA-507350]: IDV
>
> Ok, IDV image looks great. That is the reason I am trying to understand the 
> projection.
>
> As I explained in my email ,
> minimum lat is 13.8992
>  maximum lat is 65.3821
>  minimum lon is -144.517
>  maximum lon is  41.9596
>
> Rows, columns, xres and yres ( xres and yres in meters)of the lambert 
> conformal  projection:480 576 10700 10700
> > Resolution in lambert conformal is 10700 meters. When I display using IDV, 
> > I get the image with properties set to 576 X 480 pixels.
>
> If you convert the lambert projection to latlon , FOR THE SAME RESOLUTION 
> 10.7 km,
> Latitude points are roughtly,
>
> Latitude spans 52 degrees
> 1 degree is 100 km. so, roughly 520 points for a 10 km resolution
>
> Latitude spans = 103 degrees roughly - s0, 1030 grid points for a 10 km 
> resolution.
>
> When I  convert the original grib file to projectons/predefined/world in IDV 
> and display in lat/lon projection. I see IDV shows 1203 x 918 points and the 
> image looks great.
>
>
> You may notice, I use 10 km resolution which is the resolution in the grib 
> file.
>
> So, I am just interested to know if you use the same resolution.
> Can you please tell em how do you convert lambert to world?
>
> I see your source code, but I could not locate that area yet.
>
>
> Thanks a lot,
> Lalitha
>
>
>
>
>
>
>
> -----Original Message-----
> From: Unidata IDV Support [mailto:address@hidden
> Sent: Tuesday, March 22, 2011 11:53 AM
> To: Lalitha Venkatramani
> Cc: address@hidden
> Subject: [IDV #LTA-507350]: IDV
>
> > Dear Support,
> > I have a grib file with
> > Min/Max Lat/Lon 13.8992 -144.517 65.3821 -41.9596
> > Rows, columns, xres and yres ( xres and yres in meters)of the lambert 
> > conformal  projection:480 576 10700 10700
> > Resolution in lambert conformal is 10700 meters. When I display using IDV, 
> > I get the image with properties set to 576 X 480 pixels.
> >
> > I use projectons/predefined/world in IDV and display in lat/lon projection.
> > I see for the converted image ( 1203 X918) pixels.
> >
> > If the native resolution 10.7 km ( roughly 0.1 degree is maintained, I am 
> > wondering how we get 1203 X918 pixels.
> >
> > Thanks,
> > Lalitha
> >
> I loaded an image and changed the projection, I didn't see any resolution 
> change, can you give me more detail information of what you were doing?
>
>
> Yuan
> >
> >
> >
> >
> >
> >
> >
> >
> > -----Original Message-----
> > From: Unidata IDV Support [mailto:address@hidden
> > Sent: Tuesday, March 22, 2011 10:55 AM
> > To: Lalitha Venkatramani
> > Cc: address@hidden
> > Subject: [IDV #LTA-507350]: IDV
> >
> > > Dear Support,
> > >
> > > I am using IDV to display grib files.
> > >
> > > When I convert lambert to Latlon using projectons/predefined/world, I get
> > > lat/lon projection.
> > >
> > > Do you maintain the native resolution in this conversion?
> > >
> > > I can send my file and discuss more when I hear from you?
> > >
> > > Thanks,
> > > Lalitha
> > >
> >
> > Hi Lalitha,
> > I don't think the resolution being changed in this conversion.
> >
> >
> > Yuan
> > >
> >
> >
> > Ticket Details
> > ===================
> > Ticket ID: LTA-507350
> > Department: Support IDV
> > Priority: Normal
> > Status: Closed
> >
> >
>
>
> Ticket Details
> ===================
> Ticket ID: LTA-507350
> Department: Support IDV
> Priority: Normal
> Status: Open
>
>
>
> Ticket Details
> ===================
> Ticket ID: LTA-507350
> Department: Support IDV
> Priority: Normal
> Status: Open
> Link:  
> https://www.unidata.ucar.edu/esupport/staff/index.php?_m=tickets&_a=viewticket&ticketid=12991
>



Ticket Details
===================
Ticket ID: LTA-507350
Department: Support IDV
Priority: Normal
Status: Open


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