So, the frozen art book has a lot of cool stuff. Of note is the tense- everything is written as if it was pre-production. So I’ll add in my conclusions below.
Giaimo put Elsa in a triangular aqua cape decorated with snowflake patterns.
I think this describes the art work which is indeed aqua. The final result is definitely not aqua-except as an overlay of light in some scenes.
“Elsa’s palette suggesta a beautiful ice crystal,” he explains. “She is a walking effect in the way those colours reflect and refract.”
Yay! Also if you look at the artwork everything that is ice is coloured- usually in the blue shades but even to pink shades. And yellow, even if Olaf thinks it’s a bad colour for snow 😉 Interesting that the yellow is most pronounced when Elsa is attacked.
“I’m attracted to colour schemes that have close analagous relationships. It creates a striking effect.”
With her subtle mauve crew-neck top, paired with her icy blue cape and warm blue dress, Elsa’s colour palette is exquisitely harmonious.”
There is a lot of info here. Colourwise this confirms her sleeves are mauve (they tint to aqua at the wrist- it’s incredibly marked in some promo artwork and washed out in others. This is why promo-artwork can be a bit of a mixed bag- the models are rendered and then there is further editing to alter colour, proportions, add more hair etc. Like you expect in image processing for real people as well.
But the colours of the cape and the dress are reversed in the final model for the film. When you look at the artwork this is indeed the colour scheme even if it is hard to see the dress underneath! (and as per the new link below from Brittney Lee, the colours are reversed for her final design).
Also interesting to see how the sleeved undershirt is defined as having a crew neck. A crew neck is supposed to fit to the neck, Elsa has a dropped shoulder/nearly off the shoulder neckline.
For Elsa’s cape, they want to have a crisp, almost unrealistic triangle shape to it. Gravity would probbaly dip the cape down, but they want to pull that off and not have it feel distracting.
-Wayne Unten, supervising animator
Which explains some of the rigid animation is scenes inside her palace of ice vs how it is almost in free fall towards the end of the film.
Early on, Mike put Elsa, once she is the snow queen, in this stunning lace cape made out of ice. That cape set the bar very high for a design sensibility, particularly for Elsa’s world, that was very beautiful but also very modern.
John Lasseter in the Preface
We have normal ice.. there there’s Elsa’s magical ice. There are two different sets of shapes and colours. Deep ice has really strong blues as opposed to thin ice, which is greys and whites.
-Cory loftis, visual development artist.
So we have Elsa’s gown and cape as deep ice and the decorations as light ice. I think we kind of know this if we’ve had a chance to see icebergs or glaciers in person or in good photos 
Just nice to know this is probably part of the inspiration and thought process
We also came up with the idea of Elsa having a signature snowflake shape. If you saw it anywhere in the movie, you’d know it wasn’t nature, it was her.
-Dan Lund, effects artist
Michael Giaimo used the word panache to describe the design sense on Frozen, and that’s Elsa to a T, stylish original, and confident. From the column dress with leg slit and train, to the ethereal frost cape that needed to be magical yet believable, to her gorgeous almost flame licked hair.
-Keith Wilson, sim lead.
Many of our samples came from the Disney Parks costume division in Fullerton, California, where we got further education and recommendations. This collaboration translated directly to the walk-around costume interpretations for Disney’s Theme Parks, when that time came. It really helps when a studio has those kind of extensive resources!”
Costume Design in Animation – Disney’s Frozen – Tyranny of Style
So yes, yes it is possible to look at the park costume and use some of their samples for ideas
(reposting from my rpf thread 🙂 ) And adding in some quotes from Brittney Lee..
Ahah!
http://britsketch.blogspot.co.nz/2014/02/frozen-costume-design.html
I thought so! Anna does grow up between the incident and the very start of Snowman. Also Elsa has a totally different growth rate, which may also make it harder to tell the age gap between the two.
http://britsketch.blogspot.co.nz/2014/02/frozen-elsa.html
When you have fancied yourself as a bubbly mermaid for most of your life, the realization that you are actually more of a snow queen kind of hits you like a ton of ice-bricks.
This quote is more for me as I too wanted to be Ariel when I was younger 😉 I drew mermaids everywhere. Also hey, original source!
One of the first assignments I received on Elsa was a redesign of her hair. She had initially been designed with a sharper silhouette, but as her character changed it became apparent that her style needed to be refreshed. …. Oh, and magical – it would be great if it was magical, too.
Elsa doesn’t have time to fuss with her hair – she just freezes it in place and gets on with the show.
And then there is that dress. What I wouldn’t give for someone to ice-magic me that dress. Just like Elsa herself, her dress went through many, many iterations until it finally felt right for our girl. When this dress materializes, Elsa is at her most confident. She is open and free after years of controlling and containing all of her emotions. Since costumes should be designed to support the character, this dress needed to be a glorious breathe of relief.