Match Photo Lite – Part I

– Intro
A while ago I made a small structure that I called a “chiller” .. just something to stick next to a building to add interest. I figured out that when I tried to describe it to myself as “a water cooler” .. then finally a “cooling tower” that I was trying to do just that .. design a cooling tower.

Cooling_Towers_CoverSearching Google Books I found this – Cooling Towers – Wheeler Condenser & Engineering Company, Carteret, N.J. published 1922. At the front of the book it states:

(…) The inherent weakness of the spray pond, then, led to the invention and eventual perfection of the cooling tower. Early forms of cooling towers consisted of a timber framework supporting a shell filled with brushwood, horizontal slats, hollow tile cylinders and other devices intended to catch and retard the wrm watger admitted near the top of the tower. The base of the tower was either open so that air could circulate through by natural draft or it was partially enclosed and a fan or fans provided to circulate the air. (…)

That was followed by a diagram showing “The Physics of Cooling Water by Exposure to Atmospheric Air” .. and enough math to calculate the size of the cooling tower needed cool hot water from one temperature to another. This is fine for a background on the things but not that important (IMO) for modeling.

Fig.43The book contains quite a variety of cooling towers with photos and drawings of each along with how many G.P.M. capacity of each structure. Now this is where the book helps modeling .. pictures .. which are always good .. something we can follow. Page 39 has a drawing of a cooling tower that caught my eye .. being that it was relatively small .. always a big plus for modeling. The text states:

A Typical Small Wheeler Atmospheric Cooling Tower Installation. The normal capacity of this installation is 25 G.P.M. It cools the jacket water from several internal combustion engines. This type of cooling tower is ideal for service in connection with small electric light or ice and refrigerating plants.

One of the things that caught my eye were the ladders. With those to provide scaling I could use this drawing in Sketchup’s Match Photo to bring the little cooling tower back to life! I had promised Ron Pare once to write up something on using Match Photo .. so here goes. (click the images for a full-screen version which will open in a separate window)

– Crop your photo/drawing as/if needed
The first thing I did was crop that drawing so I only had the cooling tower to work with. This isn’t absolutely necessary but it does help focus on what is the central item. I renamed graphic -Fig43.jpg to Fig43_cropped.jpg (not that original I admit .. but works for me).
– Download a Copy of Sketchup
“Safe Harbor Statement” – I am using Sketchup 8 to do this. This is simply because I have the plug-ins I use where I like them and haven’t bothered switching to a newer version. This doesn’t matter as the process will be similar if not exactly the same. You can get a copy of Sketchup Make easily enough by Clicking this link. Sketchup Make is the free version – which is what I use to make 3D models – I don’t have the need to pay for the Pro version.

I’m not going to try and teach you to use Sketchup. It is IMO about as easy as falling off a log. Simply goto YouTube and enter Sketchup Tutorials in the search box. I WOULD though tell you to pay attention to “groups”, “components” and “layers” .. you can ignore that advice but you WILL regret it.

– Import the image
import_imageWell .. I suppose I might tell you to open Sketchup .. but I won’t. Click “File –> Impor

t”. Browse to the image. I have a folder I named “Match Photo for Cooling Tower”. At this point I have two photos in this folder .. Fig.43.jpg and Fig.43_cropped.jpg. I’ve found that it is VERY important to have a separate location for anything you are doing in Sketchup. It keeps your head from exploding at a later time.

The first, Fig.43.jpg is a screen-grab of the page from the book (second from the top for this article) and the second is, as the name suggests, cropped to just the part I need to work with.

You may need to select the “Files of type:” at the bottom of the window. Here, I selected “JPEG Image (*.jpg) (well .. I was working with a .jpg .. IF .. you are working with another file type then select that. If unsure what file types are supported by Sketchup the dropdown will tell you.

In addition and of most importance on the right select “Use as New Matched Photo

Then click “Open

– Import Screen
import_screen_startYou see this screen next. There is the graphic you loaded with a bunch of lines .. Solid and dashed, Red and Green. There is also a small window that opens up with the title “Match Photo”.

At this point sit back and I will explain what you are seeing on this screen.

  • Within the 3D space of Sketchup are the axes. The Global axis lines are the red, green and blue lines you see in the lower half of the graphic, extending out from a yellow box (the Origin). The red line is the X-axis, green the Y-axis and blue the Z-axis. The solid lines are in the positive direction and the dotted lines in the negative.
  • The dashed Green and Red lines are used to set the perspective of the graphic. They are called “Vanishing Point Bars”. The squares/handles on the ends of the lines are handles that you can grab and move. What we are doing is telling Sketchup where the camera was when the photo was taken (or where the artist was virtually when he drew the picture). Sketchup will use this to help you re-create the object in 3D.
  • In the Match Photo Dialog Box I selected the center Grid Style. The one on the left is for use say inside a room and the one the right looking down at something. I always use the center one for my modeling. The Spacing number sets the grid spacing. I hardly ever pay attention to this since I will be scaling the finished model.
  • Done button – don’t click this until you are .. well .. you have finished setting origin, vanish points/perspective and so on and are ready to draw and are therefore … done. If you do .. simply click the gears at the top to bring it back.
– Set Perspective Lines
During this I am using my mouse to zoom in and and out and move around the screen along with the keyboard. Once you do this a while it becomes second nature and I have to actually look so I can tell you how to do it.

  • Press and hold the Shift key then press and hold the middle/scroll wheel on the mouse. You can move the photo around the desktop
  • If you accidently click outside the graphic – on the desktop .. all the Match Photo perspective lines go away. OH NO! No problem .. In the Match Photo window click the gears and they will reappear.
  • The zoom wheel allows you to zoom in and out. This is necessary for ensuring that you move the handles to the correct points.
– Set X-axes
align_lower_red_initialI’m going to start with the lower X-axis (Red) line. No reason – you have to start somewhere. The I-Beam that supports the pan is a good place to align this axis. The cursor appears on the screen as a white glove with a circle with a slash – unless you are hovering over a hotspot. Move the cursor (glove) until you are over the right hand handle of the lower Red dashed line; left click and drag to the lower right I-Beam edge. Repeat with the left side handle and drag that to the lower left I-Beam edge.
align_lower_red_checkNow zoom in. That initial placement was simply to get the perspective line close. Zoomed in I can adjust. We are not worried about putting the handle square say on the end of the I-Beam .. but want to have it align along the edge. The right side handle isn’t that bad but the left side is off.
align_lower_red_alignedMove the cursor once again over the handles and adjust them as needed. Again .. I am paying attention to the edge of the beam .. I want the perspective line to ride along that. When happy you can zoom back out.
Note: At this point you might want to save your file. Like anything else you do on a computer .. saving the file is a GOOD thing.
align_upper_red_initialAcross the top they have two beams. I will use the ends of those to set the upper X-axis. Here’s how it looks to start.
align_upper_red_aligned.. and grab each of the handles and move them until they align along the top edge of the two beams. Again as shown .. zoom in to adjust.
– Set Y-axes
align_upper_green_alignedI aligned the Y-axis (Green) line along that beam on the end. Again .. where the handles rest is not important .. that the perspective line aligns along the edge of the beam is the critical bit. I’m zoomed in at this point so I can make sure this is the case.

align_lower_green_alignedI then aligned the lower Y-axis line along the pan edge. I used the lower portion of the lip where the shadow shows since that makes an easier process.

Once again .. I saved the file at this point .. just to be safe.
– Set the Origin
Zoom out so we can see everything. Our “Vanishing Point Bars” .. or perspective has been set. We only have to set our origin now.
This is .. IMO .. important. You need a place you can get a pretty good starting point as this is where the 3D perspective all comes together. If it is a building then the bottom corner where the side and front join would be good. It could be at the top where the sides meet also .. it depends a lot on how the photo was taken.
align_originWell .. I’m not going with either of the origin locations I suggested. The thing sits on spindly legs that stick into the ground – remember that the ground can be sloped. The top has a bunch of silly shapes. The thing sits it what looks like a giant pan the bottom ow which is curved so that’s out – but – the top of that pan offers a good place. Grab the origin (yellow box) and plop it about on the corner of the pan then zoom in to set it precisely.
done_setupZoom out. Everything is done .. so .. click the “Done” button.

Now. Sketchup knows the position of the camera or the artist that created the image. During the second part we will use this as a basis to actually create the 3D model. (Oh .. yes .. SAVE the file!)


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