diff --exclude .git -rupN ncWMS/src/java/uk/ac/rdg/resc/ncwms/controller/AbstractWmsController.java ncWMS-master/src/java/uk/ac/rdg/resc/ncwms/controller/AbstractWmsController.java
--- ncWMS/src/java/uk/ac/rdg/resc/ncwms/controller/AbstractWmsController.java	2013-04-02 11:26:35.000000000 +0200
+++ ncWMS-master/src/java/uk/ac/rdg/resc/ncwms/controller/AbstractWmsController.java	2013-04-02 11:26:53.000000000 +0200
@@ -409,6 +409,7 @@ public abstract class AbstractWmsControl
         // This throws an InvalidFormatException if the MIME type is not supported
         ImageFormat imageFormat = ImageFormat.get(mimeType);
         float vectorScale = styleRequest.getVectorScale();
+        float vectorStep = styleRequest.getVectorStep();
 
         GetMapDataRequest dr = getMapRequest.getDataRequest();
 
@@ -500,6 +501,7 @@ public abstract class AbstractWmsControl
             .opacity(styleRequest.getOpacity())
             .numColourBands(styleRequest.getNumColourBands())
             .vectorScale(vectorScale)
+            .vectorStep(vectorStep)
             .units(layer.getUnits())
             .equator_y_index(equator_y_index)
             .build();
diff --exclude .git -rupN ncWMS/src/java/uk/ac/rdg/resc/ncwms/controller/GetMapStyleRequest.java ncWMS-master/src/java/uk/ac/rdg/resc/ncwms/controller/GetMapStyleRequest.java
--- ncWMS/src/java/uk/ac/rdg/resc/ncwms/controller/GetMapStyleRequest.java	2013-04-02 11:26:35.000000000 +0200
+++ ncWMS-master/src/java/uk/ac/rdg/resc/ncwms/controller/GetMapStyleRequest.java	2013-04-02 11:26:53.000000000 +0200
@@ -56,6 +56,7 @@ public class GetMapStyleRequest
     // colour scale
     private Range<Float> colorScaleRange;
     private float vectorScale;
+    private float vectorStep;
     
     /**
      * Creates a new instance of GetMapStyleRequest from the given parameters
@@ -92,6 +93,7 @@ public class GetMapStyleRequest
         this.numColourBands = getNumColourBands(params);
         this.logarithmic = isLogScale(params);
         this.vectorScale = Float.parseFloat(params.getString("vectorScale", "1").toLowerCase());
+        this.vectorStep = Float.parseFloat(params.getString("vectorStep", "1").toLowerCase());
     }
     
     /**
@@ -224,5 +226,8 @@ public class GetMapStyleRequest
     {
         return vectorScale;
     }
-    
+    public float getVectorStep()
+    {
+        return vectorStep;
+    }
 }
diff --exclude .git -rupN ncWMS/src/java/uk/ac/rdg/resc/ncwms/graphics/ImageProducer.java ncWMS-master/src/java/uk/ac/rdg/resc/ncwms/graphics/ImageProducer.java
--- ncWMS/src/java/uk/ac/rdg/resc/ncwms/graphics/ImageProducer.java	2013-04-02 11:26:35.000000000 +0200
+++ ncWMS-master/src/java/uk/ac/rdg/resc/ncwms/graphics/ImageProducer.java	2013-04-02 11:26:53.000000000 +0200
@@ -85,6 +85,7 @@ public final class ImageProducer
      * The scale factor between vectors
      */
     private float vectorScale;
+    private float vectorStep;
     private String units;
     private int equator_y_index;
     private float arrowLength = 14.0f;
@@ -207,23 +208,26 @@ public final class ImageProducer
         }
 
         Graphics2D g = image.createGraphics();
-        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_OFF);
+        // NOTE: this turns off antialiasing !!
+        // for the vector scaling we'd like to enable antialiasing but it behaves strangely so we can't :|
+        //g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
+        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_OFF);
         g.setColor(new Color(0,0,0,100));
 
         //logger.debug("Drawing vectors, length = {} pixels", this.arrowLength);
         //List<Float> east = data.get(0);
         //List<Float> north = data.get(1);
 
-        float stepScale = 1.1f;
-        float imageLength = this.arrowLength;
+        // the vectorStep defines the distance between each vector symbol
+        // it is defined as a function of the size of the symbol glyph, multiplied by 
+        // a scaling factor supplied in the request (default = 1), plus a small margin
+        // of 5 we found to be suitable for our data
 
         if (this.style == Style.BARB) {
-            imageLength = this.barbLength * this.vectorScale;
-            stepScale = 1.2f * this.vectorScale;
-         } else {
-            imageLength = this.arrowLength * this.vectorScale;
-            stepScale = 1.1f * this.vectorScale;
-         }
+            vectorStep = 5 + this.barbLength * vectorStep;
+        } else {
+            vectorStep = 5 + this.arrowLength * vectorStep;
+        }
 
         int index;
         int dataIndex;
@@ -231,10 +235,19 @@ public final class ImageProducer
         Double mag;
         Float eastVal;
         Float northVal;
+        
 
-        for (int i = 0; i < this.picWidth; i += Math.ceil(imageLength + stepScale))
+        // get the min and max of the data, will be used to scale the vectors
+        // relative to the max and min (for non-barb vector styles)
+        float scaleMin = this.scaleRange.getMinimum().floatValue();
+        float scaleMax = this.scaleRange.getMaximum().floatValue();
+        //logger.debug("vector step = {} ", vectorStep);
+        //logger.debug("vector scale = {} ", this.vectorScale);
+        
+        // use the vectorStep to walk across the image in the x and y directions
+        for (int i = 0; i < this.picWidth; i += Math.ceil(vectorStep))
         {
-            for (int j = 0; j < this.picHeight; j += Math.ceil(imageLength + stepScale))
+        	for (int j = 0; j < this.picHeight; j += Math.ceil(vectorStep))
             {
                 dataIndex = this.getDataIndex(i, j);
                 eastVal = comps.x.get(dataIndex);
@@ -251,8 +264,19 @@ public final class ImageProducer
                       g.setStroke(new BasicStroke(1));
                       BarbFactory.renderWindBarbForSpeed(mag, radangle, i, j, this.units, this.vectorScale, j >= this.equator_y_index, g);
                     } else {
-                      // Arrows.  We need to pick the style arrow now
-                      VectorFactory.renderVector(this.style.name(), mag, radangle, i, j, this.vectorScale, g);
+                        // Arrows.  We need to pick the style arrow now
+                        //VectorFactory.renderVector(this.style.name(), mag, radangle, i, j, this.vectorScale, g);
+
+                        // use the vector scale factor when calling each individual vector symbol
+                    	
+                        // calculate the vectorScaling factor as a function of where this cell value is
+                        // in relation to the min and max. this is done by normalising the value to be between
+                        // 0 and 1, and multiplying that value by the vectorScale (default=1) ,
+                        // and then by multiplying by 4 which was a number that 'seemed right' for our data
+                        // following some experimentation
+                        float theScale = 4 * this.vectorScale * (mag.floatValue() - scaleMin) / (scaleMax - scaleMin);
+                        
+                        VectorFactory.renderVector(this.style.name(), mag, radangle, i, j, theScale, g);
                     }
                 }
             }
@@ -478,6 +502,7 @@ public final class ImageProducer
         private boolean transparent = false;
         private int opacity = 100;
         private float vectorScale = 1;
+        private float vectorStep = 1;
         private int numColourBands = ColorPalette.MAX_NUM_COLOURS;
         private Boolean logarithmic = null;
         private Color bgColor = Color.WHITE;
@@ -579,6 +604,13 @@ public final class ImageProducer
             return this;
         }
         
+        /** Sets the vectorStep (defaults to 1.0) */
+        public Builder vectorStep(float step) {
+            if (step <= 0) throw new IllegalArgumentException();
+            this.vectorStep = step;
+            return this;
+        }
+        
         /** Sets the layers units */
         public Builder units(String units) {
             this.units = units;
@@ -627,6 +659,7 @@ public final class ImageProducer
                 ? emptyRange
                 : this.scaleRange;
             ip.vectorScale = this.vectorScale;
+            ip.vectorStep = this.vectorStep;
             ip.units = this.units;
             ip.equator_y_index = this.equator_y_index;
             return ip;