[Geomoose-users] Estimating tile size

Wed Jan 30 08:07:40 PST 2013

I'd guess is in JPEGs you are looking at ~23GB and about 346GB uncompressed
for all levels.  The top level (most pixels) will be ~2/3 the size of all
of the levels combined.  I've attached a spreadsheet (ODS) that I've worked
up to estimate tile sizes.  (My guess is it will get blocked by the list,
so if anyone is interested email me.)

Which tool you use kind of depends on how you plan on serving it.  Direct
from MapServer has a different optimization strategy than if you are using
MapCache or MapProxy.  I'm not sure how portable the tools I worked on are.
 The one I did at the city was all in C and was essentially a modified
shp2img with the tile calculation added and some extra stuff removed.  What
I am using now is ruby based and relies on PostGIS for indexes and
MapServer for rendering.  The net result is the same though.

The big thing quality wise it to be sure to use -r average (GDAL) or
PROCESSING "RESAMPLE=AVERAGE" (mapserver) so the zoomed out levels aren't
all speckled as happens when using the default nearest neighbor sampling.

On Tue, Jan 29, 2013 at 1:25 PM, Basques, Bob (CI-StPaul) <
bob.basques at ci.stpaul.mn.us> wrote:

>  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> 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] *On Behalf Of *Paul Wickman
> *Sent:* Tuesday, January 29, 2013 11:28 AM
> *To:* Brent Fraser
> *Cc:* 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>
> 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 | paul at flatrockgeo.com
> www.flatrockgeo.com | twitter.com/flatrockgeo ****
>
>  ****
>
> _______________________________________________****
>
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>
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>
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>
>   ****
>
>
>
> ****
>
>  ****
>
> --
> Paul Wickman
> CTO | Flat Rock Geographics
> 612.280.5850 | paul at flatrockgeo.com
> www.flatrockgeo.com | twitter.com/flatrockgeo ****
>
>
>
> ****
>
> ** **
>
> --
> Paul Wickman
> CTO | Flat Rock Geographics
> 612.280.5850 | paul at flatrockgeo.com
> www.flatrockgeo.com | twitter.com/flatrockgeo ****
>
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>
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