I want to have a reference point or to know the coordinates of any point on an exported Image (from any view) from Revit.
For example in the attached image exported from Revit, I'd like to know the bounding box of the picture or the middle point of the picture (in X,Y coordinates) or any other reference point.
Plan image
Is there a way to extract the bounding box coordinates of the picture?
I would suggest defining two diagonally opposite points in your image file that you can identify precisely in your Revit model. Determine their image pixel coordinates, export their Revit model coordinates, and use this information to determine the appropriate scaling and translation.
The RoomEditorApp Revit add-in and its corresponding roomedit CouchDb web interface demonstrate exporting an SVG image from Revit, scaling it for display in a web browser, and transformation and calculation of exact coordinates back and forth between two environments.
Related
I aim to make an object detection model and I labelled data with a square box
If I label the images with polygon, will it be better than square?
(labelling on image of people wearing safety helmet or not)
I did try label with polygon shape on a few images and after export txt file for YOLO
why it has only 4 points in the text file as same as labelled with a square shape
how those points will represent an area that I label accurately?
1 0.573748 0.018953 0.045332 0.036101
1 0.944520 0.098375 0.108931 0.167870
You have labeled your object in a polygonial format, but when you had made a conversion to YOLO-format the information in the labelings has reduced. The picture below shows how I suppose has happend;
...where you have done polygon shape annotation (black shape). But, the conversion has "searched" the smallest x-value from the polygonial coordinate points and smallest y-value from corresponding polygonial coordinate points. And, those are the "first two" values of your YOLO-format. The same logic has happend with the "width" and "heigth" -parameters.
A good description about the idea behind the labelling and dataset is shown in https://www.youtube.com/watch?v=h6s61a_pqfM.
In short; for your purpose (for efficiency) I propose you make fast & convenient annotation using rectangles only - no time consuming polygon annotation.
The YOLO you are using very likely only has square annotation support.
See this video showing square vs polygon quality of results for detection, and the problem of annotation time required to create custom data sets.
To use polygonal masks can I suggest switching to use YOLOv3-Polygon or YOLOv5-Polygon
I am having some trouble drawing real-world objects on an SVG map.
context:
I have a map which I converted to an svg file (inkscape), this map is then displayed on a web-page with 100% width/height.
I then want to draw points on this map, those points have coordinates in mm (on a very different and bigger scale), so I need to apply a scale factor and a conversion to... pixels?
that's where the difficulty is for me, SVG file uses "user units" measure system, it is then drawn scaling everything to the frame where it is loaded, I would like to scale my real-world point coordinates system to a "user units"-like reference system so that such points can be dynamically drawn on the page.
the web page is html/svg + javascript and I am using svg.js library to draw everything on it.
any clue about how to make ma transformation to align everything up?
I am trying to extract text from an image, but within a certain area of the image and not the entire image.
I have already been able to detect where the objects of interest are and get their coordinates. Though I do not know where to start when extracting text from a specific area.
I'm using the code from this example:
https://www.codingame.com/playgrounds/38470/how-to-detect-circles-in-images
It is able to detect the circles, but I want to take it one step further and extract the numbers from the circles and tag them to their corresponding coordinate.
I'm using this example to learn how to do something similar myself, but I'm really more interested in deciding the search in a set area.
Most image processing libraries support the concept of ROIs (region of interest) or AOIs (area of interest).
The idea is to restrict processing to a subset of pixels that are usually selected by defining geometric shapes like rectangles, polygons, circles within the image coordinate system.
You can fix this issue by first cropping the image using your coordinates and try to extract text from it.
I want to add zoom capability to an app, which at its core is a spf graph app. Now I currently have no zoom, but the ability to select/move, multi-select objects on the graph in the graph window. I started to write my own code to do scaling of the objects and then work out mouse co-ordinates to map clicks and redraws correctly. I didnt complete this as I found the Gdiplus::SetPageScale function, which scales the window fine but I cannot see any GDI function I can use to map the mouse click co-ordinates from the world co-ord's to the page co-ords. I tried TransformPoints(Gdiplus::CoordinateSpaceWorld, ::Gdiplus::CoordinateSpacePage, points, 2) but this does not convert the points and the returned points are (0,0).
So is this even possible with Gdiplus or do I need to write this mapping myself? Any advice appreciated!
You don't want to use Graphics::SetPageScale() in this case. The much more general way is to use the Matrix class instead. Its Scale, Translate and Rotate methods are handy to get the matrix you need. You'll want to use the Scale() method here, possibly Translate() to change the origin.
Before you start drawing, activate the matrix with the Graphics::SetTransform() method. Anything you draw will now automatically be scaled according to the arguments you passed to the Matrix::Scale() method. Mapping a mouse position is now exceedingly simple with Matrix::TransformPoints() method, the exact same transform that was used while drawing is now applied to the mouse coordinates. Even going back from graph coordinates to mouse coordinates is simple, use the Matrix::Invert() method to obtain the inverse transform.
When GDI+ draws, it applies a world transform (which is controlled by Graphics::SetTransform, ScaleTransform, etc.) followed by the page transform (which is controlled by Graphics::SetPageScale and Graphics::SetPageUnit) to transform the points to device coordinates.
So it normally goes like this: World coordinates --[World transform]--> Page coordinates --[Page transform]--> Device coordinates
You can use Graphics::TransformPoints the way you wanted, to map mouse coordinates to world coordinates, but you have to specify Device coordinates as the source space and World coordinates as the destination space.
However, there are good reasons to do it as Hans describes with a Matrix you store separately, most notably that you shouldn't be holding on to your Graphics object for long enough to process mouse input (nor should there be a need to create one then).
I have a java applet that allows users to import a jpeg and world file from the local system. The user can then "click" draw lines on the image that was imported. Each endpoint of each line contains a set of X/Y and Lat/Long values. The XY is standard java coordinate space, the applet uses an affine transform calculation with the world file to determine the lat/long for every point on the canvas.
I have a requirement that allows a user to type a distance into a text field and use the arrow key to draw a line in a certain direction (Up, Down, Left, Right) from a single selected point on the screen. I know how to determine the lat/long of a point given a source lat/long, distance, and bearing.
So a user types "100" in the text field and presses the Right arrow key a line should be drawn 100 feet to the right from the currently selected point.
My issue is I don't know how to convert the distance( which is in feet ) into the distance in pixels. This would then tell my where to plot the point.
tcarobruce,
You are correct. The inverse transform algorithm is what I needed. Since I use java I was able to replace my "home made" transform algorithm with the java.awt.AffineTransform object which has an inverse transform function.
This seems to have solved my issue.
Thanks.
I guess you are certain your users are always uploading a raster image that is in the lat/lon wgs84 projection? Because in that case you can set a fixed coordinate transformation.
If you consider ever digitizing images from other sources with other projections, you might want to take a look at the open source geotools library: http://www.geotools.org/