Use single static image as map

will help you Ok, rebooting my vagrant VM fixed it. Don't ask me why because I don't know and it doesn't make logistical sense, in the dev env everything should be reloaded on each request.
I did nothing else except boot the VM again after Zachary asked for some fail code and it was accessible as soon as rails loaded. I spoke to a colleague shortly thereafter and he too had a very similar issue where files were not accessible until after a reboot of the machine and similarly rebooting rails itself didn't do the same job for him either.

should help you out I am kind of completing the current answer here, which fails in giving the right size of each of the arrows' tip. MATLAB does it in a way that when an arrow is nearly a dot, it doesn't have any tip, while for long arrows it shows a big tip, as the following image shows.

    double l_max = -10;

    for (int y = 0; y < img_sz.height; y+=10)                                                           // First iteration, to compute the maximum l (longest flow)
    {
        for (int x = 0; x < img_sz.width; x+=10)
        {
            double dx = cvGetReal2D(velx, y, x);                                                        // Gets X component of the flow
            double dy = cvGetReal2D(vely, y, x);                                                        // Gets Y component of the flow

            CvPoint p = cvPoint(x, y);

            double l = sqrt(dx*dx + dy*dy);                                                             // This function sets a basic threshold for drawing on the image

            if(l>l_max) l_max = l;
        }
    }


    for (int y = 0; y < img_sz.height; y+=10)
{
    for (int x = 0; x < img_sz.width; x+=10)
    {
        double dx = cvGetReal2D(velx, y, x);                                                        // Gets X component of the flow
        double dy = cvGetReal2D(vely, y, x);                                                        // Gets Y component of the flow

        CvPoint p = cvPoint(x, y);

        double l = sqrt(dx*dx + dy*dy);                                                             // This function sets a basic threshold for drawing on the image
        if (l > 0)
        {
            double spinSize = 5.0 * l/l_max;                                                        // Factor to normalise the size of the spin depeding on the length of the arrow

            CvPoint p2 = cvPoint(p.x + (int)(dx), p.y + (int)(dy));
            cvLine(resultDenseOpticalFlow, p, p2, CV_RGB(0,255,0), 1, CV_AA);

            double angle;                                                                           // Draws the spin of the arrow
            angle = atan2( (double) p.y - p2.y, (double) p.x - p2.x );

            p.x = (int) (p2.x + spinSize * cos(angle + 3.1416 / 4));
            p.y = (int) (p2.y + spinSize * sin(angle + 3.1416 / 4));
            cvLine( resultDenseOpticalFlow, p, p2, CV_RGB(0,255,0), 1, CV_AA, 0 );

            p.x = (int) (p2.x + spinSize * cos(angle - 3.1416 / 4));
            p.y = (int) (p2.y + spinSize * sin(angle - 3.1416 / 4));
            cvLine( resultDenseOpticalFlow, p, p2, CV_RGB(0,255,0), 1, CV_AA, 0 );

        }
   }
}

will help you If I'm understanding: you have some static HTML files that you can't/don't want to change, with relative URL link. In that case, just construct your MVC route so that the relative paths work. For example, let's say the relative paths are like this:

js/script.js
css/style.css

With these it helps Here is a way:
You remove image from carousel items, and affect an image in the carrousel-inner background property in css.

.carousel-inner{
   background-image: url("http://upload.wikimedia.org/wikipedia/commons/3/3e/Tux-G2.png");
    background-position: center center;
    background-repeat: no-repeat;
    height:200px;
  }

  .carousel-caption{
     top:1em; 
    }

<div class="container">
    <div class="span8">
    <div id="myCarousel" class="carousel slide">
        <ol class="carousel-indicators">
            <li data-target="#myCarousel" data-slide-to="0" class=""></li>
            <li data-target="#myCarousel" data-slide-to="1" class="active"></li>
            <li data-target="#myCarousel" data-slide-to="2" class=""></li>
        </ol>
        <div class="carousel-inner">
            <div class="item">

                <div class="carousel-caption">
                    <h4>First Thumbnail label</h4>
                    <p>Cras justo odio, dapibus ac facilisis in, egestas eget quam. Donec id elit non mi porta gravida at eget metus. Nullam id dolor id nibh ultricies vehicula ut id elit.</p>
                </div>
            </div>
            <div class="item active">

                <div class="carousel-caption">
                    <h4>Second Thumbnail label</h4>
                    <p>Cras justo odio, dapibus ac facilisis in, egestas eget quam. Donec id elit non mi porta gravida at eget metus. Nullam id dolor id nibh ultricies vehicula ut id elit.</p>
                </div>
            </div>
            <div class="item">

                <div class="carousel-caption">
                    <h4>Third Thumbnail label</h4>
                    <p>Cras justo odio, dapibus ac facilisis in, egestas eget quam. Donec id elit non mi porta gravida at eget metus. Nullam id dolor id nibh ultricies vehicula ut id elit.</p>
                </div>
            </div>
        </div>
        <a class="left carousel-control" href="#myCarousel" data-slide="prev">‹</a>
        <a class="right carousel-control" href="#myCarousel" data-slide="next">›</a>
    </div>
    </div>
</div>

I hope this helps . here is my view page...

<?php $images = json_decode($row->image); if(!empty($images)) {
echo '<img class="primary-image" src="'.base_url().'images/'.$images[0].'" alt="" />';
if(isset($images[1])) { 
    echo '<img class="secondary-image" src="'.base_url().'images/'.$images[1].'" alt="" />';
} } ?>