Index in position 1 is invalid. Array indices must be positive integers or logical values.

I used ginput(2) to get initial and goal configuration for path planner, however, when i want to check their feasibility with respect to map and the obstacles i got this error: Index in position 1 is invalid. Array indices must be positive integers or logical values.

map_original = imread('env5.jpg'); 

% Resize map
map_reaized = imresize(map_original,[500 500]);

%  Call convert2binary() function to conver Image to binary using thresholding
map_binary = convert2binary(map_reaized);
map = imbinarize(map_binary);
% get the source and destination nodes from inputs
imshow(map);
[p1, p2] = ginput(2);

source = p1';
goal = p2';

% Check feasibility
if ~feasiblePoint(source,map)
    error('source lies on an obstacle or outside map');
end
if ~feasiblePoint(goal,map)
    error('goal lies on an obstacle or outside map');
end

function [binary] = convert2binary(map_original)
% Following MATLAB function will take a grayscale 
% or an RGB image as input and will return a
% binary image as output 

[x, y, z] = size(map_original);
   
     % if Read Image is an RGB Image then convert 
     % it to a Gray Scale Image For an RGB image 
     % the value of z will be 3 and for a Grayscale
     % Image the value of z will be 1
   
    if z==3
         map_original = rgb2gray(map_original);
    end
   
    % change the class of image 
    % array from 'unit8' to 'double'
    map_original = double(map_original);
   
    % Calculate sum of all the gray level
    % pixel's value of the GraySacle Image
    sum = 0;
    for i = 1:x
         for j = 1:y
        sum = sum + map_original(i, j);
        end
     end
   
    % Calculate Threshold value by dividing the 
    % calculated sum by total number of pixels 
    % total number of pixels = rows*columns (i.e x*y) 
    threshold = sum/(x*y);
    
    % Create a image array having same number
    % of rows and column as Original image
    % with all elements as 0 (Zero).
    binary = zeros(x, y);
   
    % iterate over all the pixels of Grayscale 
    % Image and Assign 1 to binary(i, j), if gray
    % level value is >=  threshold value     
    % else assign 0 to binary(i, j) .
   
    for i = 1:x
     for j = 1:y
        if map_original(i, j) >= threshold
                binary(i, j) = 1;
        else
            binary(i, j)=0;
        end
     end
    end
end

function feasible = feasiblePoint(point,map)
feasible = true;
% check if collission-free spot and inside maps
if ~(point(1)>=1 && point(1)<= size(map,1) && point(2)>= 1 && point(2)<= size(map,2) && map(point(1),point(2)) == 1)
    feasible = false;
end

Answer 1

[KSSV]

When you use ginput to extract the points, you may end up getting decimals and you are trying to index these points; as matlab indices should be possitive integers or logical you are ending up with error. The work around is, round your extracted points to integers. Change this function:

function feasible = feasiblePoint(point,map)  % point are decimals 
feasible = true;
% check if collission-free spot and inside maps
if ~(point(1)>=1 && point(1)<= size(map,1) && point(2)>= 1 && point(2)<= size(map,2) && map(point(1),point(2)) == 1)
    feasible = false;
end

to

function feasible = feasiblePoint(point,map)
point = round(point) ;   % <--- point is rounded to avoid error 
feasible = true;
% check if collission-free spot and inside maps
if ~(point(1)>=1 && point(1)<= size(map,1) && point(2)>= 1 && point(2)<= size(map,2) && map(point(1),point(2)) == 1)
    feasible = false;
end

[YAAQOB AL-JAMALI]

thank you @KSSV