[mapserver-users] MapServer dynamic map creation - Is this possible?

[Daniel Walton]

Frank,

Thanks for your very concrete and helpful response! We're creating images
that are chipped from infrared imagery using wildfire perimeter shapes. Thus
each image will be an individual layer. I am aware that 40MB is small
compared to world maps, but I wanted to know what the scalability of
MapServer would be, and if, given that potentially hundreds of server
instances per day may be created, the whole thing might grind to a halt.
What kind of disk, CPU, memory, and bandwidth requirements would you expect
such a service to require (back of the napkin calculation)?

Thanks again,
Dan


On Mon, Sep 28, 2009 at 11:11 AM, Frank Warmerdam <warmerdam at pobox.com>wrote:

> Dan Walton wrote:
>
>> I am new to WMS, so bear with my ignorance please.
>> I have a service that processes imagery and outputs large TIFF + World
>> file
>> images (5-40 MB), and some shapefiles. Currently these images have no
>>
>
> Dan,
>
> Note that 5-40MB files are normally considered small in this domain.
>
>  pyramid or tiling. I would like to further make the images web map
>> friendly
>> and my thought is that WMS and MapServer is the way to go. We will likely
>> be
>> creating dozens or perhaps hundreds of these images per day. This needs to
>> run on Windows alongside or within IIS.
>> So I have a volley of questions for anyone who might have answers. Feel
>> free
>> to skip any:
>>
>> 1. Can MapServer even do this, that is, host several large images and
>> allow
>> new ones to be added on the fly via the api?
>>
>
> Yes, this is possible.  One question is whether the images are intended
> to be treated as a mosaic or as distinct, individually addressable layers.
>
> If they are to be a mosaic, then you want to read up on tileindexes which
> allow you to treat a set of images as a single layer - a mosaic.  Then your
> task boils down to creating a static mapfile, and dynamically adding files
> to
> the tileindex as they are created.
>
> If each is a distinctly addressable product then they should each either
> have an associated layer in a mapfile or you need a distinct map for each
> image.
>
> I will say it is not prudent to have hundreds of layers in a map - it
> becomes
> quite cumbersome, so I think it would be better to treat each image as a
> distinct WMS service with it's own mapfile (possibly generated on the fly
> from a database record).
>
>  2. Can each image be a map layer or does each image need its own mapserver
>> instance?
>>
>
> As above, either is possible.
>
>  3. Does the OSGeo4W include utilities to tile and pyramid the images or do
>> I
>> have to arrange for that myself?
>>
>
> OSGeo4W's gdal package includes the required tools.  In particular to take
> a TIFF image ("in.tif") and convert it to an optimized form with internal
> tiling and overviews ("out.tif") you would do something like:
>
>  gdal_translate -co TILED=YES in.tif out.tif
>  gdaladdo out.tif 2 4 8 16 32 64
>
> OSGeo4W is setup primarily for Apache, so to use it with IIS there
> will be some manual fiddling you will need to do yourself.  However,
> people do it, so it is doable.
>
> Best regards,
> --
>
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam<http://pobox.com/%7Ewarmerdam>
> and watch the world go round - Rush    | Geospatial Programmer for Rent
>
>
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