[Blindmath] Working of the device.

Sun Jan 20 15:03:50 UTC 2013

I am a little puzzled from reading these messages, particularly a 
statement in a previous message about this: "Also the user here need not 
be required to be too knowledgeable about Cartesian co ordinate system 
or geometry."

The below message I am replying to describes precisely inputting the 
shape by using cartesian co-ordinates.

To describe this further, I will use the below example of inserting a 
30cm wide by 10cm high rectangle in the top left hand corner of the page 
(NOTE: probably not a good thing to draw when using A4 paper as it will 
not fit).

The below example for the device said I would need to find button 1, 
then move to the right three units to get button 3, move down one unit 
to button 6 and move left three units to get button 4. As these are laid 
out in a grid I am effectively selecting cartesian co-ordinates and as 
these units of each button are not necessarily the same as the unit I am 
working in (cm) I need to remember to apply a scale of 10cm = 1 button. 
How would one draw with such a device a rectangle 23cm by 11cm?

Now to compare with drawing with SVG (possibly SVGDraw or other 
software), I would say, start at co-ordinate (0cm,0cm), move to 
co-ordinate (30cm,0cm), move to (30cm,10cm) and move to co-ordinate 
(0cm,10cm) and close the path. So in this case I did not need to convert 
from cm to any other unit, so the drawing 23cm by 11cm problem can be 
done easy ( (0cm,0cm) -- (23cm,0cm) -- (23cm,11cm) -- (0cm,11cm) -- 
cycle ). Also it is worth noting that some software (I am thinking of 
PGF/TikZ as that is something I know) do have shortcuts for rectangles, 
you need only specify the top left co-ordinate and bottom right 
co-ordinate, the other two can be calculated automatically by the computer.

I don't know whether SVGDraw can do this, but other software (again 
PGF/TikZ is one I know is capable) would allow you to then move and 
rotate a drawn shape, this can make calculating the co-ordinates much 
easier (eg. if we wanted to rotate the 30cm by 10cm rectangle by 30 
degrees, we could do the original drawing with it horizontal and easy 
co-ordinates and then rotate it by 30 degrees). How would one go about 
drawing such a shape with the device? Do you need to draw the shape as 
it will appear or can one do such movements after entering the shape?

I will agree that sometimes cartesian co-ordinates are not easy to work 
with for drawing certain shapes, an equilateral triangle is not easy but 
much easier when using polar co-ordinates and again some software such 
as PGF/TikZ do allow using polar co-ordinates to draw a shape. While I 
think SVGDraw does not support using polar co-ordinates it could easily 
be added i would imagine. However a physical device which has buttons 
laid out in a grid shape will not be able to be adapted to use polar 
co-ordinates and I imagine due to so few buttons (20x16) will not be 
able to draw an equilateral triangle accurately.

Finally, I do believe that if one wishes to draw accurately then a 
understanding of co-ordinate systems and geometry is very valuable. 
Without an understanding of these concepts one is simpling guessing what 
they are drawing.

Sorry if this sounds very negative, but I do have concerns whether this 
will achieve what it is meant to and sometimes only by viewing something 
critically can it overcome its problems. Here are a few questions to 
consider:
* Should one be trying to make it that one need not understand 
co-ordinate systems or geometry? Will this really be of advantage to the 
person in the long term?
* Does this really lower the effort in understanding co-ordinate 
systems, to me it only seems to provide a physical representation of a 
co-ordinate system and only one co-ordinate system at that.
* Is 20x16 input points sufficient? It may pose issues for rectangles 
and certainly will for other shapes like equilateral triangles, 
pentigons, etc (fairly basic shapes) where edges will not be horizontal 
or vertical.
* Possibly is it really going to be worth the development cost? What I 
mean by that is one could draw on tactile graph paper (which is 
something which already exists) and use that to obtain the co-ordinates 
they need to input into the computer should they find calculating the 
co-ordinates in there mind too difficult and this would hopefully over 
time make the person understand the co-ordinates. Tactile graph paper 
also is more flexible as one can draw to a fraction of a unit. Sometimes 
the low tech solution can be best, something even acknowledged on my 
computing post graduate course.

Michael Whapples
On 20/01/2013 06:26, Kiran wrote:
> Dear Amanda,
>
> I shall explain how the device works. The device has 20 columns and 16 rows of tactile plungers those act as input points. For description purpose I shall scale it to a regular 4 / 4 matrix of keys that we used to have on mobile device. So the keys would be numbered like 1 2 3 in the first row
> Followed by 4 5 6, in second row followed by 7 8 9 in third row.
>
> Now say if we want to draw a rectangle 30 by 10 cm in the word file. Here is what we need to do.
>
> 1. Select the shape rectangle from the control panel, the user can feel the shape himself as there is a 3d shape on the panel.
>
> 2. To draw a rectangle we need 4 input points. So I press the number 1 key. I scale the distance from one key to other as say 10 cm. now I can go to the key no 3 as they are in the same row and I can feel them in a straight line. So I go to the key no 3 and press it.
>
> 3. Then I follow down from key no 3 to key no 6, since 3 and 6 key are in the same colum, and press 6, that means now I have pressed three keys they are 1,3,6.
>
> 4. Again I slide my finger on to the row of key 6 and come until key no 4. Since key no 1 and 4 are in the same colum, and I press it.
>
> That means I have pressed 1,3,6,4.  Keys, kindly note that 1 & 3 are in same row similarly 6,4 are in the same row.
>
> So I am myself drawing the shape, then the associated software shall input the diagram of a rectangle in any of the application you chose.
>
> The device has 320 plungers that are lined up in 20 columns and 16 keys so the user has a wide array of plungers that help him in drawing all the possible shapes and the software shall assist him in all stages.
>
>
>
> Kiran S Deshpande
>   
>
>
>   
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