Free Graph Digitizer

[Imogen Petrusky]

Plotdigitizeris an online data extraction tool that allows users to extract data from images in numerical format. In short, it reverse-engineers your visual graphs into numbers. The software comes with plenty of useful and time-saving features.

Upload the graph image to PlotDigitizer, select the graph type, calibrate the axis/axes, and start marking points and data values of the points that are automatically generated. You can also export these data to other formats. For more, read our official documentation.

Online PlotDigitizer's app is a free tool available for online use only. The tool is free and allows users to extract data from various graphs though it comes with limited features. For full access to additional features, like auto-tracing, dataset storage, you have to purchase a pro license

DigitizeIt digitizer software replaces a digitizer tablet. Sometimesit is necessary to extract data values from graphs, e.g. in mostscientific publications only plots but no data values are published.

DigitizeIt makes it easy to actually get back numbersfrom such a plot!

DigitizeIt is try-before-you-buy software. The unregistered version is for evaluation purposes only and will stop working after 21 days.

If you want to continue using DigitizeIt after the evaluation period, you must purchase a license key. The license does not expire and is valid for all future updates of DigitizeIt on all supported operating systems.

The online registration process is done by MyCommerce. It is easy, secure and fast. You can pay using several different payment methods and currencies. If you pay by credit card, you will receive the license key immediately after purchase.

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You find all answers in ourCustomer Care Center.

GetData Graph Digitizer is a program built for getting raw data out of visual graphs for analytical purposes. Most of the comparative data are usually visualized by graphs and charts. This software helps you in converting these visual data in to figures and export in to sheets in desired formats.

The software works on simple procedure of opening the targeted graph then setting your own scale to measure against. Digitize it automatically or manually and then export or copy the raw data in to TXT, XLS, XML, DXF or EPS files. The software supports TIFF, PEG, BMP and PCX formats of images. There are two algorithms for automatic digitizing and a simple to use manual method. You can save the progress and comeback to finish anytime you want. You can copy the converted values to the clipboard and then export in to text or excel or AutoCAD or PostScript files.

This is a tool which can be very helpful in offices where most of the records are stored in visual graphs and in cases where the raw data has been lost. It is unique software with an easy to use interface.

What I'd like is that the user graphically defines, at first, the X axis domain (in the picture from 0 to 2000) and the Y axis domain (in the picture from 0 to 180) and then picks some points on the curve and, once this procedure has ended, I need to have the points added to a Datagridview that I've already done. Could anyone suggest me where to start?

I need to activate this sub when I press a specified button. Until I press the button, the mouse position, even if clicking inside the picturebox, must not be stored. If tried to put the picturebox sub inside the Button_click sub but It doesn't work.

Another event that I have to program is that - when pressing the mouse button inside the picturebox - on the first click, Form4 must be shown; at the second click, Form5 must be shown; at the third click, Form6 must be shown. From the fourth click (until the user has ended to pick points), the mouse position must be stored.

Those of you who know me know I am quite enamored with a little freeware application called Plot Digitizer. If you are unfamiliar with it, the application allows to to create CSV (Comma Separated Value) files from the lines in an image. Meaning that if you have, for instance, a pump curve as a .pdf or .jpg file, then you can pretty quickly capture the curve shapes and load them into a spreadsheet to create a chart that is an electronic version of the curve.

Once the curve is in the form of a spreadsheet. you can do math on the lines in it. For instance, you can use the affinity laws to project a new impeller size from a know impeller size. or you can plot a system curve from the data you collect in a pump test and the square law.

This link will take you to a page on our commissioning resources web site where I provide more information, and this link will take you to a page where I provide a spreadsheet template that will let you create a formatted pump curve pretty easily from the CSV files you capture with plot digitizer.

My goal in this post is to show you an idea that came to me one day out in the field that saved the day for me and involved using plot digitizer in a way I had not thought of before. Since it happened while I was working at a really interesting chilled water plant that had some unique features, I thought I would give you a peak at those things also.

There were two cool features in the plant I will be discussing that I wanted to highlight in addition to illustrating my new Plot Digitizer application. But if you want to jump straight to that, the links below will let you do that (or jump to any of the other topics for that matter). Each section has a Back to Contents link that brings you back here.

The plant was a variable flow primary/secondary plant. Unlike current technology chillers, back when this plant was designed, the chiller technology would not deal well with flow variation in the evaporator. In fact, in the olden days, before we had realized that we needed to pay attention to energy efficiency, the most common chilled water plant design configuration was a constant flow arrangement and a big driver for that was protecting the chiller tube bundles from frosting up and freezing. But you ended up with large pumps moving the design flow rate at the design head for all of the operating hours.

The variable flow primary secondary design evolved as a way to allow the flow rate to the loads to vary with the load profile, saving a significant amount of pump energy, while maintaining a steady flow rate through the chillers, which protected them. My point in bringing this up here is simply to let you know about the configuration of the plant I am about to discuss, not to explain variable flow primary/secondary plant theory. But, if you want to know more about that, you will find a couple of resources at this link.

Aside from the size and quality of the plant, there were two technologies they had in place that provided for some added interest. So, I wanted to briefly highlight them here so you recognize them if you run into them.

A hydraulic coupling is very similar to the torque converter in an automatic transmission and is the blue piece of machinery between the motor (the dark gray thing on the left) and the pump on the right (the black thing with the silver pipes attached to it) in the picture above.

While fairly efficient at full speed and full load, these drives are much less efficient than a current technology variable frequency drive at part load. That means they represent a good retrofit target and the plant operating team has that on their list of improvements for this year.

From a retrocommissioning standpoint, for a project where you might need to document the inefficiency of the drive to support your case for replacing it, its kind of cool that you could pretty easily document the efficiency of the drive by logging flow and temperature rise across the heat exchanger because that is where the losses show up.

Another interesting thing about this technology when you contrast it with the variable frequency drive most of us are more accustomed to is that the motor is ahead of the drive. That means the motor needs to be sized for the brake horsepower the pump needs at its input shaft, plus the losses in the drive. In contrast, a variable frequency drive serving a motor serving a pump supplies the pump energy plus the motor efficiency losses.

You may wonder why anyone would use even use a hydraulic drive. My guess is that at the time they were installed, a variable frequency drive for a 450 hp 4,160 volt motor would have been pretty spendy.

For example, in 1980, when I specified my first variable speed drive for a 40 hp air handling unit motor, my choices were a variable frequency drive that cost about $50,000 and was the size of two motor control center sections. Or, I could use an eddy current clutch which cost about $20,000. The eddy current clutch was significantly less efficient at part load, but given the price difference, it was the better choice at the time.

So my guess is that a similar economic assessment prevailed when they built this plant and these drives probably made sense back then. Plus, they are basically mechanical devices so a mechanically inclined person can probably fix one in a pinch.

Most people in the industry are familiar with water side free cooling cycles that leverage the capacity of cooling towers at low wet bulb temperatures to create chilled water directly with out the need to operate a chiller. Typically, this involves operating the cooling towers to produce water colder than is required by the chilled water system and using a plate and frame heat exchanger in between the condenser water system and the chilled water system to transfer the energy.

My point here is that there is another way to accomplish the cycle with out the cost of the heat exchanger and the pumps it requires and several of the chillers in the Gaylord plant were equipped with this feature.

More specifically, some chillers can be configured in a way that allows an operating mode to occur where control valves bypass the compressors and expansion device. The compressor bypass allows refrigerant vapor to migrate from the evaporator to the condenser due to the vapor pressure difference created if the temperature in the condenser is lower than the temperature in the evaporator. The expansion device bypass allows liquid refrigerant to circulate by gravity back from the condenser back to the evaporator.

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