Vertical lines artifacts while using ShapeInserter of Vision toolbox ?

Hello everyone,

I am trying to solve a problem that you guys may have had if you used the toolbox.

I am using ShapeInserter to draw arrows on an image generated out of a code.

I use a function "arrows_coordinates" to provide polygons coordinates of an arrow with start point, end point and, line thickness and width and length of the arrow in pixels.

Then, I draw the polygoned arrows in the image using step but sometimes undesired vertical lines on the image appear coming with arrows, not all of them). Attached is an example of an image with 5 arrows in the center of the image and all of them having the vertical line problem.

All of them haveing the problem :

Not all of them having the problem :

Detail :

From the same examples here is the useful code :

% create arrows
shapeInserter = vision.ShapeInserter('Shape','Polygons',...
                                     'BorderColor','Custom',...
                                     'CustomBorderColor', [255 0 0],...
                                     'Fill', 1,...
                                     'FillColor','Custom',...
                                     'CustomFillColor', [255 0 0],...
                                     'Opacity', 1,...
                                     'Antialiasing', 1);

% id which show arrows:
for id = 1:npoints
   arrows(id,:) = int32(arrow_coordinates(x_mosaic(id)-25,...
                                          y_mosaic(id)-25,...
                                          x_mosaic(id)-1,...
                                          y_mosaic(id)-1,...
                                          3, 10, 12));
end

mosaic = step(shapeInserter, mosaic, arrows);

"x_mosaic" and "y_mosaic" is the array with the coordinates of points showed by the arrows and "mosaic" is the image

The arrow_coordinate function :

function tab = arrow_coordinates(x1,y1,x2,y2,LW,W,H)
% tab = array with points coordinates of the polygoned arrow
% 
% x1,y1 = start point of the arrow
% x2,y2 = end point of the arrow
% LW = line thickness in pixels
% W = width of arrow head in pixels
% H = length of arrow head in pixels

opp = y2-y1;
adj = x2-x1;
hyp = ((y2-y1)^2+(x2-x1))^0.5;

xa = x2;
ya = y2;

xb = x2 - H*adj/opp - W/2*opp/hyp;
yb = y2 - H*opp/hyp + W/2*adj/hyp;

xc = x2 - H*adj/hyp - LW/2*opp/hyp;
yc = y2 - H*opp/hyp + LW/2*adj/hyp;

xd = x1 - LW/2*opp/hyp;
yd = y1 + LW/2*adj/hyp;

xe = x1 + LW/2*opp/hyp;
ye = y1 - LW/2*adj/hyp;

xf = x2 - H*adj/hyp + LW/2*opp/hyp;
yf = y2 - H*opp/hyp - LW/2*adj/hyp;

xg = x2 - H*adj/hyp + W/2*opp/hyp;
yg = y2 - H*opp/hyp - W/2*adj/hyp;

tab = [xa ya xb yb xc yc xd yd xe ye xf yf xg yg];

end

I keep looking after the problem I will tell you here if I find something. This post is in case some of you know or are interested in the problem.

Answer 1

[Yan Zhu]

Hi, I come across the same problem

Does anybody have a solution?

Answer 2

[Amichay amitay]

This seems to be a bug in this feature when using LineWidth that is larger than 1. I managed to bypass this by adding the line (in your case arrow) on a image of the same size but zero values. Then used imdilate to make the lines wider. Then used the non-zero values to write the original image. For example, adding on Image Img lines (defined in LinesVar) with width 10 is as follows: Tmp=Img*0; shapeInserter = vision.ShapeInserter('Shape', 'Lines', 'BorderColor', 'White','LineWidth',1); Tmp = step(shapeInserter, Tmp, int32(LinesVar)); Tmp = imdilate(Tmp,strel('disk',5)); Img (Tmp>0)= 255; %for example

Answer 3

[DGM]

See also:

https://www.mathworks.com/matlabcentral/answers/411443-problem-with-insertshape

It's probably an earlier version the same bug.