[Geomoose-users] Estimating tile size

Tue Jan 29 11:25:11 PST 2013

Paul,

The fastest approach has and seems to still be using MapServer to generate the tiles, via a script.  Jim K. has even verified this within the last couple of weeks, since he tried improving on the original system we used here and came back to it in the end with some minor upgrades.

It doesn't really matter how you get there, even if it takes a little longer.  I think there are some MapServer utilities that we used originally on this layer.  You may want to experiment for yourself on what works best for what.

Also, in our experience, we've had best results using Jpeg (NOT JPEG2000!!) for aerials and PNGs for overlay tiles.

Bobb

From: Paul Wickman [mailto:paul at flatrockgeo.com]
Sent: Tuesday, January 29, 2013 1:18 PM
To: Basques, Bob (CI-StPaul)
Cc: Brent Fraser; geomoose-users at lists.osgeo.org
Subject: Re: [Geomoose-users] Estimating tile size

Thank you kindly, Bob.  Did you use gdal2tiles.py or is there another utility you like better?

On Tue, Jan 29, 2013 at 1:08 PM, Basques, Bob (CI-StPaul) <bob.basques at ci.stpaul.mn.us<mailto:bob.basques at ci.stpaul.mn.us>> wrote:
Paul,

For reference, I'm looking at a layer here for the City, about 56sq mi coverage at 6in pxels.  Using Jpeg tiles, 1000x1000pxels (500x500 ground units).

Keep in mind that the City is not a rectangle . . . but the levels break down like so:

(L0) ~27,000 tiles = 1.5 GB
(L1) ~ 4500 tiles = 420MB
(L2) ~ 1140 Tiles = 123MB
(L3) ~ 293 tiles = 35MB
(L4) ~ 83 tiles = 9.4MB
(L5) ~ 28 tiles = 2.5MB

These were generated from MRSID files originally, so I can't give you a number on disksize, since MRSIDs are basically compiled Pyramids to begin with.  I have some other layers that started as flat rasters such as your TIFFs if you want me to put something together for those, let me know.

Bobb

From: geomoose-users-bounces at lists.osgeo.org<mailto:geomoose-users-bounces at lists.osgeo.org> [mailto:geomoose-users-bounces at lists.osgeo.org<mailto:geomoose-users-bounces at lists.osgeo.org>] On Behalf Of Paul Wickman
Sent: Tuesday, January 29, 2013 11:28 AM
To: Brent Fraser
Cc: geomoose-users at lists.osgeo.org<mailto:geomoose-users at lists.osgeo.org>
Subject: Re: [Geomoose-users] Estimating tile size

Yes, bytes.  Zowie...   I have a TIFF of an air photo for one of our other municipalities (also 6-inch resolution), which is 20 GB (uncompress).  That coverage is only ~40 square miles.  So, for a single ~800 square mile county also at 6-inch resolution I'd potentially be looking at 400 GB for the uncompressed source or...  somewhere on the order of ~800 GB tiled?  Does that sound right?

Anybody from MnGeo on this list with any input?

On Tue, Jan 29, 2013 at 11:15 AM, Brent Fraser <bfraser at geoanalytic.com<mailto:bfraser at geoanalytic.com>> wrote:
Do you mean how many bytes?

Looking at my Landsat tile pyramids (levels 4 to 12), they're about the same number of bytes (hmm, I expected them to be double...)

But my source images:
    - no compression on existing files (tiffs, e.g not jpeg)
    - 3 band (color) imagery

The resulting tiles:
    - compressed PNGs
    - four bands (one alpha channel for transparency)

So  my guess is somewhere between "same size" to "double the number of bytes" (unless the source imagery is compressed, then it will be 5 to 10 times larger)

Best Regards,

Brent Fraser
On 1/28/2013 5:53 PM, Paul Wickman wrote:
Greetings,

I know this type of question goes around often in various flavors.  Difficult to estimate exact size of rendered tiles, but thought I'd try to get some opinions.

I see this questions asked in a variety of ways and I know it's not exactly precise on how to get the answer, but I'll throw my question out to see what I get ;)

We have a client who would like us to tile and serve up high-resolution aerial photography that they own. The area is about 800 square miles and the imagery is 6-inch resolution. They'd like to be able to view the imagery at zoom levels 11 through 20 (with level 20 being 1 pixel=6 inches). Is there any way at all to determine how large a resulting raster tile set might be?

Many thanks,
  Paul

--
Paul Wickman
CTO | Flat Rock Geographics
612.280.5850<tel:612.280.5850> | paul at flatrockgeo.com<mailto:paul at flatrockgeo.com>
www.flatrockgeo.com<http://www.flatrockgeo.com> | twitter.com/flatrockgeo<http://twitter.com/flatrockgeo>

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--
Paul Wickman
CTO | Flat Rock Geographics
612.280.5850<tel:612.280.5850> | paul at flatrockgeo.com<mailto:paul at flatrockgeo.com>
www.flatrockgeo.com<http://www.flatrockgeo.com> | twitter.com/flatrockgeo<http://twitter.com/flatrockgeo>

--
Paul Wickman
CTO | Flat Rock Geographics
612.280.5850 | paul at flatrockgeo.com<mailto:paul at flatrockgeo.com>
www.flatrockgeo.com<http://www.flatrockgeo.com> | twitter.com/flatrockgeo<http://twitter.com/flatrockgeo>
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