[postgis-users] Applying a formula to more than two Raster Layers

[David Haynes]

You can use the map algebra function combined with Common Table expressions.


On Tue, May 9, 2017 at 4:20 AM, David Westcott <
david.westcott at uk.rsagroup.com> wrote:

> Dear Post GIS Users
>
>
>
> Is there a way in PostGIS of applying a formula to more than two Raster
> layers?
>
>
>
> For example, I want to derive a new Raster Layer calculated as follows:
>
>
>
> Constant1 x Layer1 x (Layer2 ^ Constant2) + Constant3 x Layer3 x (Layer4 ^
> Constant4) + Constant5 x Layer5 x (Layer6 ^ Constant6)
>
>
>
> Where  Constant1, Constant2, Constant3, Constant4, Constant5 & Constant6
> are fixed constants.
>
>                 Layer1, Layer2, Layer3, Layer4, Layer5 & Layer6 are
> already derived Raster Layers.
>
>                 The ‘^’ sign represents raised to the power of. (i.e. 3^2
> = 9).
>
>
>
> How would I apply such a formula in PostGIS?
>
>
>
> Kind Regards
>
>
>
> David Westcott
>
>
>
> Please consider the environment before printing this email. RSA are proud
> to be a responsible business - www.rsagroup.com/corporate-responsibility
>
> ************************************************************
> ************************************************************
> *********************************************************
> Royal & Sun Alliance Insurance plc (No. 93792). Registered in England &
> Wales at St. Mark's Court, Chart Way, Horsham, West Sussex, RH12 1XL.
>
> Authorised by the Prudential Regulation Authority and regulated by the
> Financial Conduct Authority and the Prudential Regulation Authority.
> For your protection, telephone calls may be recorded and monitored.
> The information in this e-mail is confidential and may be read, copied or
> used only by the intended recipients. If you have received it in error
> please contact the
> sender immediately by returning the e-mail. Please delete the e-mail and
> do not disclose any of its contents to anyone.
> No responsibility is accepted for loss or damage arising from viruses or
> changes made to this message after it was sent.
> ************************************************************
> ************************************************************
> *********************************************************
>
> _______________________________________________
> postgis-users mailing list
> postgis-users at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/postgis-users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20170510/37709272/attachment.html>