If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#21
|
|||
|
|||
Printing off approach plates on demand?
John R. Copeland wrote:
More specifically, Jepp plates are vector graphics, not raster images. They are rendered into a raster image only at time of display, so lines and edges won't appear fuzzy at high zoom levels. That means each displayable image is constructed to the full resolution of your display device only *after* you select a subsection of the chart, such as the chart header, or the profile view, etc. for display. That uses a little extra real-time image-processing computation, but the result is an immensely better image than PDFs give us. PDF is inherently vector graphics too (they *can* contain raster scanned images, but the approach plates are vector). I just opened up the HPN ILS-16 plate in Adobe Reader and zoomed in to 6400%. No jaggies. PDF is pretty much just PostScript with a few minor restrictions and packaged up nicely in a standard file format. If you zoom in to about 800% on some of the standard symbols (vortac, displaced threshold) on the charts, you can even see some classic PostScript coding errors where they don't handle mitre clipping properly at the corners of polygons. PostScript has built-in mechanisms to handle these (ahem) corner cases, but whoever did coded up the postscript driver didn't do it right. |
#22
|
|||
|
|||
Printing off approach plates on demand?
"Roy Smith" wrote in message ...
John R. Copeland wrote: That uses a little extra real-time image-processing computation, but the result is an immensely better image than PDFs give us. PDF is inherently vector graphics too (they *can* contain raster scanned images, but the approach plates are vector). I just opened up the HPN ILS-16 plate in Adobe Reader and zoomed in to 6400%. No jaggies. Thanks, Roy. I didn't really know how PDFs worked internally. My subjective impression has always been that PDFs are a little fuzzy in ALL sizes. PDFs on my 640x480 PDA are especially objectionable. Probably the Adobe Reader software in my PDA is incompetent. It may have been designed for QVGA resolution instead of VGA. |
#23
|
|||
|
|||
Printing off approach plates on demand?
I do a lot of work with AutoCad, which of course is a vector graphic
application, and you can zoom to your heart's content. When I need to deliver content to those who cannot read AutoCad files, I often print to PDF, but the limitations are severe - to the point of rendering the content unreadable - that is unreadable to a sufficient and necessary level of detail. All PDF's are not created equal either. Download some charts from Airnav and the same charts from AOPA, and you will have two different file sizes, and a very notable difference in resolution (the Airnav being far better). GF |
#24
|
|||
|
|||
Printing off approach plates on demand?
|
#25
|
|||
|
|||
Printing off approach plates on demand?
In a previous article, "John R. Copeland" said:
"Roy Smith" wrote in message ... PDF is inherently vector graphics too (they *can* contain raster scanned images, but the approach plates are vector). I just opened up the HPN ILS-16 plate in Adobe Reader and zoomed in to 6400%. No jaggies. Thanks, Roy. I didn't really know how PDFs worked internally. My subjective impression has always been that PDFs are a little fuzzy in ALL sizes. Depends where you get the plates from. For a long time, various web sites had approach plates that they'd scanned themselves, where the PDF contained a raster image. But then NACO released their own PDFs, where the plates are in vector format and eminently scalable. I believe some web sites are still doing the scanned raster ones. -- Paul Tomblin http://xcski.com/blogs/pt/ The Write Many, Read Never drive. For those people that don't know their system has a /dev/null already. -- Rik Steenwinkel, singing the praises of 8mm Exabytes |
#26
|
|||
|
|||
Printing off approach plates on demand?
Peter wrote:
I am amazed Adobe don't do the corners right, given they invented and specified the format. They should have *the* definitive rasteriser for it. What makes you think Adobe did anything wrong? I think whoever wrote the postscript driver for the NOS/FAA/whatever folks didn't generate the correct postscript. Looks like they neglected to do a "closepath" at the appropriate places. |
#27
|
|||
|
|||
Printing off approach plates on demand?
In article ,
Greg Farris wrote: I do a lot of work with AutoCad, which of course is a vector graphic application, and you can zoom to your heart's content. When I need to deliver content to those who cannot read AutoCad files, I often print to PDF, but the limitations are severe - to the point of rendering the content unreadable - that is unreadable to a sufficient and necessary level of detail. If the PDF files are unreadable, then I'd say AutoCad isn't very smart about how it generates PDFs. Or, more likely, it depends on some default system-supplied print driver to generate them, and that does a bad job. Done properly, PDF files should be just as zoomable as the AutoCad originals. |
#28
|
|||
|
|||
Printing off approach plates on demand?
In article ,
(Paul Tomblin) wrote: Depends where you get the plates from. For a long time, various web sites had approach plates that they'd scanned themselves, where the PDF contained a raster image. But then NACO released their own PDFs, where the plates are in vector format and eminently scalable. Right, the scanned ones were horrible. Anybody who's still scanning printed plates just doesn't get it. And anybody who's still using scanned plates doesn't get it either. One can abuse PDF just like one can abuse anything. |
#29
|
|||
|
|||
Printing off approach plates on demand?
|
#30
|
|||
|
|||
Printing off approach plates on demand?
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Air Force One Had to Intercept Some Inadvertent Flyers / How? | Rick Umali | Piloting | 29 | February 15th 06 04:40 AM |
Nearly had my life terminated today | Michelle P | Piloting | 11 | September 3rd 05 02:37 AM |
PC/PDA based approach plates | Nathan Young | Instrument Flight Rules | 5 | January 30th 05 01:15 AM |
Approach Plates on PDA (PIREP) | Stan Prevost | Instrument Flight Rules | 10 | December 18th 04 04:21 AM |
USAF = US Amphetamine Fools | RT | Military Aviation | 104 | September 25th 03 03:17 PM |