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I'm using Python 2.7 and OpenCV 3.x for my project for omr sheet evaluation using web camera.
While finding the number of white pixels in around the center of circle,I came to know that the intensity values are wrong, but it shows the correct values in MATLAB when I'm using imtool('a1.png').
I'm using .png image (datatype uint8).
just run the code and in the image go to [360:370,162:172] coordinate and see the intensity values.. it should not be 0.
find the images here -> a1.png a2.png
Why is this happening?
import numpy as np
import cv2
from matplotlib import pyplot as plt
#select radius of circle
radius = 10;
#function for finding white pixels
def thresh_circle(img,ptx,pty):
centerX = ptx;
centerY = pty;
cntOfWhite = 0;
for i in range((centerX - radius),(centerX + radius)):
for j in range((centerY - radius), (centerY + radius)):
if(j < img.shape[0] and i < img.shape[1]):
val = img[i][j]
if (val == 255):
cntOfWhite = cntOfWhite + 1;
return cntOfWhite
MIN_MATCH_COUNT = 10
img1 = cv2.imread('a1.png',0) # queryImage
img2 = cv2.imread('a2.png',0) # trainImage
sift = cv2.SIFT()# Initiate SIFT detector
kp1, des1 = sift.detectAndCompute(img1,None)# find the keypoints and descriptors with SIFT
kp2, des2 = sift.detectAndCompute(img2,None)
FLANN_INDEX_KDTREE = 0
index_params = dict(algorithm = FLANN_INDEX_KDTREE, trees = 5)
search_params = dict(checks = 50)
flann = cv2.FlannBasedMatcher(index_params, search_params)
matches = flann.knnMatch(des1,des2,k=2)
good = []# store all the good matches as per Lowe's ratio test.
for m,n in matches:
if m.distance < 0.7*n.distance:
good.append(m)
if len(good)>MIN_MATCH_COUNT:
src_pts = np.float32([ kp1[m.queryIdx].pt for m in good ]).reshape(-1,1,2)
dst_pts = np.float32([ kp2[m.trainIdx].pt for m in good ]).reshape(-1,1,2)
M, mask = cv2.findHomography(src_pts, dst_pts, cv2.LMEDS,5.0)
#print M
matchesMask = mask.ravel().tolist()
h,w = img1.shape
else:
print "Not enough matches are found - %d/%d" % (len(good),MIN_MATCH_COUNT)
matchesMask = None
img3 = cv2.warpPerspective(img1, M, (img2.shape[1],img2.shape[0]))
blur = cv2.GaussianBlur(img3,(5,5),0)
ret3,th3 = cv2.threshold(blur,0,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU)
ret,th2 = cv2.threshold(blur,ret3,255,cv2.THRESH_BINARY_INV)
print th2[360:370,162:172]#print a block of image
plt.imshow(th2, 'gray'),plt.show()
cv2.waitKey(0)
cv2.imwrite('th2.png',th2)
ptyc = np.array([170,200,230,260]);#y coordinates of circle center
ptxc = np.array([110,145,180,215,335,370,405,440])#x coordinates of circle center
pts_src = np.zeros(shape = (32,2),dtype=np.int);#x,y coordinates of circle center
ct = 0;
for i in range(0,4):
for j in range(0,8):
pts_src[ct][1] = ptyc[i];
pts_src[ct][0] = ptxc[j];
ct = ct+1;
boolval = np.zeros(shape=(8,4),dtype=np.bool)
ct = 0;
for j in range(0,8):
for i in range(0,4):
a1 = thresh_circle(th2,pts_src[ct][0],pts_src[ct][1])
ct = ct+1;
if(a1 > 50):
boolval[j][i] = 1
else:
boolval[j][i] = 0
I have a code in matlab as below. the code is very confusing. Now i need to decide the north west part of the disk (270-360) degree if the fuel type are f3 and f5, then it is a shia. i need to return yes or no for shia.
% base path
fireline_path = 'Documents/fireline/';
% EOSD landcover file
landcover_file = fullfile(fireline_path,'landcover/EOSD/083O_lc_1/083O_lc_1.TIF');
[landcover,cmap_landcover,R_landcover0] = geotiffread(landcover_file);
proj_landcover = geotiffinfo(landcover_file);
pixelsize = 25; % 25m UTM grid
% trim raster to area around town of Lake
i_trim = 3001:3500;
j_trim = 3001:3500;
landcover = landcover(i_trim,j_trim);
[x11,y11] = pix2map(R_landcover0,i_trim(1),j_trim(1));
R_landcover = makerefmat(x11,y11,pixelsize,-pixelsize);
% read in damaged propeties and get their locations in grid
damage_shapefile = fullfile(fireline_path,'work/slavelake/damaged_properties_SL.shp');
damage = shaperead(damage_shapefile);
x_damage = [damage(~strcmp({damage.Damage},'Undamaged')).X];
y_damage = [damage(~strcmp({damage.Damage},'Undamaged')).Y];
[i_damage, j_damage] = map2pix(R_landcover,x_damage,y_damage);
ind_damage = sub2ind(size(landcover),round(i_damage),round(j_damage));
% create landcover -> fuel mappings
fuelmappings = zeros(max(landcover(:)),1);
ind_vegclass = [52,81,82,83,100,211,221,231]; % indicies of classes present that are vegetation
veg_loadings = [...
3,...'Shrub Low'
3,...'Wetland-treed'
3,...'Wetland-shrub'
1,...'Wetland-herb'
1,...'Herbs'
5,...'Coniferous-dense'
5,...'Broadleaf-dense'
5]; %Mixedwood-dense'
fuelmappings(ind_vegclass) = veg_loadings;
landcover(landcover==0) = 1; % set nodata cells to 1, this will map to no fuel
fuelmap = fuelmappings(landcover);
% create binary fuel map (F3 or F5)
fuelmapbw = fuelmap>=3;
%%
% flag pixels within 1/2 mile of dense areas
shiasum = zeros(size(landcover)); % initialize summary
disp('Percent of damaged/destroyed properties in SHIA:')
densitythresholds = .25;%[.75, .67, .5, .33, .25];
for densitythreshold = densitythresholds
% create filter to calculate shia (create a disk and then zero out unwanted
% pixels)
shiadistmiles = .5; %miles
shiadistmeters = shiadistmiles*unitsratio('meters','miles');
shiadistpix = shiadistmeters/pixelsize;
hshia = fspecial('disk',shiadistpix);
hshia(1:floor(shiadistpix),:) = 0;
xy = -floor(shiadistpix):floor(shiadistpix);
[X,Y] = meshgrid(xy,fliplr(xy));
f70 = -tan(deg2rad(70))*X;
hshia(Y<f70) = 0;
f20 = -tan(deg2rad(20))*X;
hshia(Y>f20) = 0;
hshia(hshia>0) = 1;
hshia = hshia/sum(hshia(:));
close all
shiavals = filter2(hshia,fuelmapbw);
shia = filter2(hshia,fuelmapbw) > densitythreshold;
linkimage(fuelmapbw,shia)
hold on
plot(j_damage,i_damage,'x')
hold off
propsinshia = sum(shia(ind_damage))/numel(ind_damage);
disp(['With threshold of ' num2str(densitythreshold) ':'])
disp(propsinshia * 100)
outfile = [fireline_path 'shia/SlaveLake_'...
num2str(densitythreshold*100,'%02d') '.tif'];
geotiffwrite(outfile,shia,R_landcover,...
'CoordRefSysCode',proj_landcover.GeoTIFFCodes.PCS)
shiasum = shiasum+shia;
end
lookup = [0 fliplr(densitythresholds) * 100];
shia = lookup(shiasum+1);
outfile = [fireline_path 'shia/SlaveLake_v2.tif'];
geotiffwrite(outfile,uint8(shia),R_landcover,...
'CoordRefSysCode',proj_landcover.GeoTIFFCodes.PCS)
I have to draw a hipsometric map on a 3D plot. I have two vectors 1x401 (named xLabels and yLabels) which are the geo coordinates, and401x401(namedA`) matrix with the altitude data. To plot the data I use:
surf(xLabels, yLabels,A,'EdgeColor','None','Marker','.');
which leads to something like that:
But i would like to have something like that:
On the second image, only the surface is plotted, while my image looks like pillars.
I tried even make my vectors to 401x401 using meshgrid but it did not have any effect.
Do you have any idea what I should change?
#EDIT
I checked for X and Y data. I quess is too small interval (0.0083), but when i try plot good second of upper plots with same interval it draws correctly.
#EDIT2:
sizeX = 4800;
sizeY = 6000;
pixdegree = 0.0083; % 1 pixel is 0.0083 degree on map
intSize = 2;
lon = 37 + (35/60);
lat = 55+ (45/60);
fDEM = 'E020N90';
fHDR = 'E020N90.HDR';
[startXY, endXY] = calcFirstPixel(lon, lat); %calc borders for my area
f = fopen('E020N90.DEM');
offset = (startXY(1,2)*sizeX*intSize)+(startXY(1,1)*intSize);
fseek(f, offset,0); %seek from curr file pos
x = 0;
A = [];
BB = [];
jump = (intSize*sizeX)-(401*2);
while x<401
row = fread(f, 802);
fseek(f, jump, 0); %jump 2 next row
A = [A row];
x = x+1;
end
fclose(f);
A = A';
A = A(:,2:2:802);
m1 = min(A(:)); %wartość minimalna dla naszej podziałki
m2 = max(A(:)); %wartość maksymalna dla naszej podziałki
step = m2/8; % będzie 8 kolorów
highScale = m1:step:m2-step; %wartości graniczne dla każdego z nich
%handles.axes1 = A;
colormap(hObject, jet(8));
startXtick = 20 + pixdegree*startXY(1,1);
endXtick = 20 + pixdegree*endXY(1,1);
startYtick = 90 - pixdegree*endXY(1,2);
endYtick = 90 - pixdegree*startXY(1,2);
[XX,YY] = ndgrid(startXtick:pixdegree:endXtick,startYtick:pixdegree:endYtick);
xLabels = startXtick:pixdegree:endXtick;
yLabels = startYtick:pixdegree:endYtick;
surf(xLabels, yLabels,A,'EdgeColor','None','Marker','.');
set(gca,'YDir','normal');
grid on;
view([45 45])
And .DEM files
function [startXY, endXY] = calcFirstPixel(lon,lat)
global fHDR;
format = '%s %s';
f = fopen(fHDR);
cont = textscan(f, format);
LonStart = str2double(cont{1,2}{11,1});
LatStart = str2double(cont{1,2}{12,1});
diffPerPix = str2double(cont{1,2}{13,1});
fclose(f);
x = LonStart;
countX = 0
y = LatStart;
countY= 0;
while x<lon
x=x+diffPerPix
countX = countX +1;
end
while y>lat
y=y-diffPerPix
countY = countY+1;
end
startXY= [countX-200 countY-200];
endXY = [countX+200 countY+200];
end
Many questions exist already covering how to detect collisions between a line segment and a circle.
In my code, I am using Matlab's linecirc function, then comparing the intersection points it returns with the ends of my line segments, to check that the points are within the line (linecirc assumes an infinite line, which I don't have/want).
Copying and adding some sprintf calls to the linecirc function shows that it is calculating points as intended. These seem to be being lost by my function.
My code is below:
function cutCount = getCutCountHex(R_g, centre)
clf;
cutCount = 0;
% Generate a hex grid
Dg = R_g*2;
L_b = 62;
range = L_b*8;
dx = Dg*cosd(30);
dy = 3*R_g;
xMax = ceil(range/dx); yMax = ceil(range/dy);
d1 = #(xc, yc) [dx*xc dy*yc];
d2 = #(xc, yc) [dx*(xc+0.5) dy*(yc+0.5)];
centres = zeros((xMax*yMax),2);
count = 1;
for yc = 0:yMax-1
for xc = 0:xMax-1
centres(count,:) = d1(xc, yc);
count = count + 1;
centres(count, :) = d2(xc, yc);
count = count + 1;
end
end
for i=1:size(centres,1)
centres(i,:) = centres(i,:) - [xMax/2 * dx, yMax/2 * dy];
end
hold on
axis equal
% Get counter for intersected lines
[VertexX, VertexY] = voronoi(centres(:,1), centres(:,2));
numLines = size(VertexX, 2);
for lc = 1:numLines
segStartPt = [VertexX(1,lc) VertexY(1,lc)];
segEndPt = [VertexX(2,lc) VertexY(2,lc)];
slope = (segEndPt(2) - segStartPt(2))/(segEndPt(1) - segStartPt(1));
intercept = segEndPt(2) - (slope*segEndPt(1));
testSlope = isinf(slope);
if (testSlope(1)==1)
% Pass the x-axis intercept instead
intercept = segStartPt(1);
end
[xInterceptionPoints, yInterceptionPoints] = ...
linecirc(slope, intercept, centre(1), centre(2), L_b);
testArr = isnan(xInterceptionPoints);
if (testArr(1) == 0) % Line intersects. Line segment may not.
interceptionPoint1 = [xInterceptionPoints(1), yInterceptionPoints(1)];
interceptionPoint2 = [xInterceptionPoints(2), yInterceptionPoints(2)];
% Test if first intersection is on the line segment
p1OnSeg = onSeg(segStartPt, segEndPt, interceptionPoint1);
p2OnSeg = onSeg(segStartPt, segEndPt, interceptionPoint2);
if (p1OnSeg == 1)
cutCount = cutCount + 1;
scatter(interceptionPoint1(1), interceptionPoint1(2), 60, 'MarkerFaceColor', 'r', 'MarkerEdgeColor', 'k');
end
% Test if second intersection point is on the line segment
if (interceptionPoint1(1) ~= interceptionPoint2(1) || interceptionPoint1(2) ~= interceptionPoint2(2)) % Don't double count touching points
if (p2OnSeg == 1)
cutCount = cutCount + 1;
scatter(interceptionPoint2(1), interceptionPoint2(2), 60, 'MarkerFaceColor', 'r', 'MarkerEdgeColor', 'k');
end
end
end
end
% Plot circle
viscircles(centre, L_b, 'EdgeColor', 'b');
H = voronoi(centres(:,1), centres(:,2));
for i = 1:size(H)
set(H(i), 'Color', 'g');
end
end
function boolVal = onSeg(segStart, segEnd, testPoint)
bvX = isBetweenOrEq(segStart(1), segEnd(1), testPoint(1));
bvY = isBetweenOrEq(segStart(2), segEnd(2), testPoint(2));
if (bvX == 1 && bvY == 1)
boolVal = 1;
else
boolVal = 0;
end
end
function boolVal = isBetweenOrEq(end1, end2, test)
if ((test <= end1 && test >= end2) || (test >= end1 && test <= end2))
boolVal = 1;
else
boolVal = 0;
end
end
It creates a hexagonal grid, then calculates the number of crossings between a circle drawn with a fixed radius (62 in this case) and a specified centre.
The scatter calls show the locations that the function counts.
Implementing sprintf calls within the if(p1OnSeg == 1) block indicates that my function has chosen fictitious intersection points (although it then deals with them correctly)
if (interceptionPoint1(1) > -26 && interceptionPoint1(1) < -25)
sprintf('p1 = [%f, %f]. Vx = [%f, %f], Vy = [%f, %f].\nxint = [%f, %f], yint = [%f, %f]',...
interceptionPoint1(1), interceptionPoint1(2), VertexX(1,lc), VertexX(2,lc), VertexY(1,lc), VertexY(2,lc),...
xInterceptionPoints(1), xInterceptionPoints(2), yInterceptionPoints(1), yInterceptionPoints(2))
end
Outputs
p1 = [-25.980762, 0.000000]. Vx = [-25.980762, -25.980762], Vy = [-15.000000, 15.000000].
xint = [-25.980762, -25.980762], yint = [0.000000, 0.000000]
A picture shows the strange points.
Sorry for the very long question but - why are these being detected. They don't lie on the circle (displaying values within a mylinecirc function detects the intersections at around (-25, 55) and (-25, -55) or so (as an infinite line would expect).
Moving the circle can remove these points, but sometimes this leads to other problems with detection. What's the deal?
Edit: Rotating my grid pattern created by [Vx, Vy] = voronoi(...) and then removing points with very large values (ie those going close to infinity etc) appears to have fixed this problem. The removal of 'large' value points seems to be necessary to avoid NaN values appearing in 'slope' and 'intercept'. My guess is this is related to a possible slight inclination due to rotation, coupled with then overflow of the expected intercept.
Example code added is below. I also edited in Jan de Gier's code, but that made no difference to the problem and so is not changed in the question code.
%Rotate slightly
RotAngle = 8;
RotMat = [cosd(RotAngle), -sind(RotAngle); sind(RotAngle), cosd(RotAngle)];
for i=1:size(centres,1)
centres(i,:) = centres(i,:) - [floor(xMax/2) * dx, floor(yMax/2) * dy]; %Translation
centres(i,:) = ( RotMat * centres(i,:)' ); %Rotation
end
% Get counter for intersected lines
[VertexX, VertexY] = voronoi(centres(:,1), centres(:,2));
% Filter vertices
numLines = size(VertexX, 2);
newVx = [];
newVy = [];
for lc = 1:numLines
testVec = [VertexX(:,lc) VertexY(:,lc)];
if ~any(abs(testVec) > range*1.5)
newVx = [newVx; VertexX(:,lc)'];
newVy = [newVy; VertexY(:,lc)'];
end
end
VertexX = newVx';
VertexY = newVy';
numLines = size(VertexX, 2);
Still appreciating answers or suggestions to clear up why this is/was occuring.
Example values that cause this are getCutCountHex(30, [0,0]) and ...(35, [0,0])
I cant reproduce your problem, but the thing I did notice is that your onSeg() function might be wrong: it returns true if the testpoint lies in the rectangle with two of the four corner points being segStart and segEnd.
A function that returns true iff a point is on (or more accurate: close enough to) the line segment (segStart,segEnd) could be:
function boolVal = onSeg(segStart, segEnd, testPoint)
tolerance = .5;
AB = sqrt((segEnd(1)-segStart(1))*(segEnd(1)-segStart(1))+(segEnd(2)-segStart(2))*(segEnd(2)-segStart(2)));
AP = sqrt((testPoint(1)-segEnd(1))*(testPoint(1)-segEnd(1))+(testPoint(2)-segEnd(2))*(testPoint(2)-segEnd(2)));
PB = sqrt((segStart(1)-testPoint(1))*(segStart(1)-testPoint(1))+(segStart(2)-testPoint(2))*(segStart(2)-testPoint(2)));
boolVal = abs(AB - (AP + PB)) < tolerance;
end
an approach that I found in one of the anwers here: Find if point lays on line segment. I hope that solves your problem.
I have designed an application called CLegend, which allows to build a multicolumn legend, whose code is
function CLegend(hax,numcol,Ley)
%# Inputs
% hax : handle of the axes object to which belongs the legend
% numcol: number of columns for the legend
% Ley: text strings (labels) for the legend
set(hax,'Units','normalized','Position',[0.1 0.1 0.8 0.8]);
set(hax,'Units','characters');
posAx = get(hax,'Position');
insAx = get(hax,'TightInset');
[legend_h,object_h] = legend(hax,Ley,'Units','characters','Location',...
'South','Orientation','vertical');
posl = get(legend_h,'Position');
numlines = length(Ley);
if (numlines<numcol)
numcol = numlines;
end
numpercolumn = ceil(numlines/numcol);
if (mod(numlines,numpercolumn) == 0)
numcol = numlines/numpercolumn;
end
l = zeros(1,numlines);
a = zeros(1,numlines);
h = zeros(1,4);
for j=1:numlines
h = get(object_h(j),'Extent');
l(j) = h(3);
a(j) = h(4);
set(object_h(j),'Units','characters');
end
lmax = posl(3)*max(l);
hmax = posl(4)*max(a);
hLine = object_h(numlines+1);
xdata = get(hLine, 'xdata');
dx = xdata(2)-xdata(1);
di = 2;
sheight = hmax;
height = hmax*numpercolumn-sheight/2;
line_width = dx*posl(3);
spacer = xdata(1)*posl(3);
delta1 = spacer + line_width + spacer + lmax;
delta2 = line_width + spacer + lmax + spacer;
delta3 = lmax + spacer + line_width + spacer;
factx = 1/(posl(3)*numcol);
facty = 1/(hmax*numpercolumn);
width_l = numcol*delta1;
set(legend_h, 'Position', [posAx(1) + 0.5*(posAx(3)-width_l) posl(2) ...
width_l numpercolumn*hmax]);
col_ind = -1;
row_ind = -1;
j = 0;
for i=1:numlines,
if strcmpi(orient,'horizontal'),
if mod(i,numcol)==1,
row_ind = row_ind+1;
end
col_ind = mod(i,numcol)-1;
if col_ind == -1,
col_ind = numcol-1;
end
else
if numpercolumn==1 || mod(i,numpercolumn)==1,
col_ind = col_ind+1;
end
row_ind = mod(i,numpercolumn)-1;
if row_ind == -1,
row_ind = numpercolumn-1;
end
end
if (i==1)
linenum = i+numlines;
else
linenum = linenum+di;
end
labelnum = i;
set(object_h(linenum), 'ydata',facty*[height-row_ind*sheight ...
height-row_ind*sheight]);
set(object_h(linenum), 'xdata', factx*[spacer + j*delta2 ...
spacer + j*delta2 + line_width]);
set(object_h(linenum+1), 'ydata',facty*(height-row_ind*sheight));
set(object_h(linenum+1), 'xdata', factx*(spacer+line_width/2));
set(object_h(labelnum), 'Position', [j*delta3+spacer*2+line_width ...
height-row_ind*sheight]);
if (mod(i,numpercolumn)== 0)
j = j + 1;
end
end
opl = get(legend_h,'OuterPosition');
set(hax, 'Position',[posAx(1) posAx(2)+opl(4) posAx(3) posAx(4)-opl(4)]);
set(legend_h, 'OuterPosition',[opl(1) (posAx(2)-insAx(2))/2 opl(3) opl(4)]);
set([hax,legend_h],'Units','normalized');
end
I have problems with it. I have tried it with a more complicated code but similar to this one that appears below.
function qq
fh = figure('Units','characters');
GrapWin = uipanel ('Parent',fh,'Units','characters','title','Graphic',...
'Position',[135 5 120 40]);
haxes = axes('Parent',GrapWin,'Units','normalized','Position',[0.1 0.1 0.8 0.8]);
PanVD = uipanel('Parent',fh,'Units','characters','Position',[55 5 30 10],...
'title','Dependent Variable');
VDlh = uicontrol('Parent',PanVD,'Style','listbox','Units',...
'normalized','Position',[0 0 1 1],'String',{'X','Y','Z'},'Value',1,...
'Callback',#VDLhCallback);
T = 0:pi/100:2*pi;
X = sin(T);
xlabel(haxes,'Time');
title(haxes,'Sine Function');
plot(haxes,T,X);
CLegend(haxes,3,{'Var X'});
function VDLhCallback (src,evt)
value = get(VDlh,'Value');
switch value
case 1
title(haxes,'Sine Function');
plot(haxes,T,X);
CLegend(haxes,3,{'Var X'});
case 2
title(haxes,'Cosine Function');
Y = cos(T);
plot(haxes,T,Y);
CLegend(haxes,3,{'Var Y'});
case 3
Z = tan(T);
title(haxes,'Tangent Function');
plot(haxes,T,Z);
CLegend(haxes,3,{'Var Z'});
end
end
end
It happens something that I do not understand because the first time that CLegend is called the legend appears not centered (respect to axes) but the following callings through the listbox options it does is centered.
Other problem that occurs is that if I delete the command line
set(haxes,'Units','normalized')
then, although the legend is centered, the axes appear with a reduced size.
I also have found that the first time Clegend is calles, the position of the axes (variable posAx) is different from the following callings (in which posAx is always the same).
I have thought that when the units were changed, the position of the object was not changed but this problem arises doubts inside my mind.
In the Figure Properties documentation, it is said of Unit
This property affects the CurrentPoint and Position properties. If you
change the value of Units, it is good practice to return it to its
default value after completing your computation so as not to affect
other functions that assume Units is the default value.
Can it explain your problems?
After a lot of proofs, I have found that my problem was the resizing of the figure. The first time CLegend was called the figure window had its original size. The following calls of CLegend happened with the figure windows maximized.