Did they go mad at Google?

I was just searching references for the Microsoft Press "MCTS Self-Paced Training Kit (Exam 70-536)" book with Google, and surprisingly for me all the results had beneath them the following advise: "Este sitio puede dañar tu equipo" (original text as I was searching in Spanish), that is something like "This site might damage your computer" (using the keywords MCTS, self-paced, 536).

And I was so surprised because among others, I could find in such "damaging" site list Microsoft's msdn.microsoft.com or www.amazon.com as well.

Moreover, when I clicked on any of them, I was redirected to another Google's page where I was advised to not to go to the searched page (or if I did it, it would be under my responsibility ;)).

My first reaction (I should be more quiet, I know), has been to change my default search engine from Google to "Live Search"... Next thoughts: Responsibles of those firms wouldn't be very happy if they notice that their sites are not reachable through Google (as all we now, nobody uses it...).

Finally, two minutes after, I repeated the same search (same keywords) in Google, and then the unexplainable took place: The same results appeared now without the evil advise.

Can you understand that? Are their developments properly tested at Google before publishing them on the Internet? How much business of those companies may have been affected in this lapse of time?

3D Modelling

Cuando hablamos de catastro 3D, deberíamos tener en cuenta estos principios:

• Existencia de la necesidad de registrar objetos catastrales (unidades catastrales, bienes) en tres dimensiones, porque las tradicionales dos dimensiones no son suficientes.
• Un objeto catastral 3D debe considerarse pues como un volumen, frente a una superficie (representación habitual).
• No siempre va a existir un case perfecto entre el concepto de planta y el volumen ocupado por un objeto catastral.
• El volumen ocupado por una unidad no tiene porque ser un cuerpo simple, aunque normalmente será una agrupación de cuerpos simples regulares.
• Dentro de un volumen pueden existir plataformas que deben considerarse ya que suponen un aprovechamiento de superficie (¿también se podrían considerar como volúmenes virtuales cuando algun lado queda abierto?, no me gusta).
• De aplicación general: Edificaciones, túneles, cuevas, etc.