Zoandar

Looks like some of you have been discussing alternate methods of doing this scenery creation process, but resample.exe is a compiler used in the original process to compile the x.bmp, x watermask.bmp and x blendmask.bmp into the BGL file you will load into FSX to use your created scenery. Hope that helps. :)

Hi Folks, Glad to see this thread is still alive. I am still hammering away at making my own scenery, after several years now. I am not going to go back and read this thread to see what has transpired since my last visit, but I wanted to share something I consider to be a real blessing when working with SBuilderX313 and making a very large hydro-poly along a shoreline. (Most of my work centers on the Great Lakes area of the US). In the midst of all that left-clicking for the little points which sometimes add up into the thousands to define the elevation edge of a complex shoreline, one false slip of the right-click button will close the hydro-poly and you'll be stuck having to start all over again. I have tried concatenating and/or overlapping multiple hydro-polys when this happens and always had bad results in the end. So I found myself really wishing I had a way to disable the right mouse button temporarily. Google found me a few options, and the one I am using is a nifty little freeware utility called Mouse Disabler. It is a small window that opens with several check-boxes to disable different mouse functions, such as right-click, scroll wheel, etc. But it also has a check-box for the left-click function. So turning that on plunges you into the interesting world of Windows OS with no mouse. Not recommended for the impatient. :) Once checked, the desired function immediately turns off. I can left click away following a coastline and press the right click button repeatedly with no effect, until such time as I go back to the Mouse Disabler window and left-click the checkbox to turn that disabled function back on. Then I can right-click to close the poly. I hope this discovery brings the same relief I have found from many encounters with this annoyance to others who are using SBuilderX313. Enjoy!

I had never heard of these folks before. I just looked at their Ohio scenery, specifically to get a look at the lakeshore. It appears they do not have the problem of the messed up shoreline like the previous scenery I bought has. Either they found a way to fix it (maybe similar to my method) or else they are getting their imagery from somewhere other then Google Earth, where the shoreline ugliness can be seen if you zoom in closely. They have very nice scenery! But its kind of expensive. $40 for a state. That would add up rather quickly. Still, it is nice to see someone is doing the whole US, instead of just the areas the general public deems "scenic".

Ah, thanks for the explanation. I don't know if you knew about VERO-FS scenery, but back before they shut down I bought all their California scenery as it was being released. That was before I learned I could make my own. They had some very nice scenery, but had no plans to do anything over in the Great Lakes region. Eventually I found Sim-Savvy, where I got my first scenery for this area. Financial troubles shut them down, but not before I was able to buy several Midwest states. It is in that scenery the lakeshore issues appeared, which led me to my current project, because I just had to "do something" to make the lakeshores much better. I have just had to switch from using Virtual Earth satellite imagery to using Yahoo instead, while working Upper Michigan. Yahoo has some far better imagery up here. I am not familiar with the MSE name. Where did you get it?

Um......you're using terms with which l am not familiar. Was all that you descibed good or bad? lol :) If you want you can exclude autogen from your scenery. I had to do that somewhat as I worked my way past the Detroit Michigan area. They were putting industrial autogen in the midst of water bodies and residential neighborhoods. Easy enough to fix. In a way I kind of miss the default autogen trees and buildings. Too bad we don't have some magic wand that can make them appear where they are really supposed to be, short of placing each one manually. I use Instant Scenery to place objects when I want them, but I can't imagine trying to do a whole state.

Check your PMs. I think one element of how high the quality goes in satellite imagery is the geographical area itself. I've read that some 20+ LOD imagery can be had for the UK, but I've never worked that part of the globe. I can tell you that one certain area in the state of Michigan refused to cooperate with SBX map acquisition until I broke it down into small segments. Once I got about 50 miles away, things were fine again to capture the full 2200 cell map. I would love to get a look into the inner workings of how these servers process satellite imagery. I am doing an area of shoreline in Upper Michigan now that has totally screwed up coloration, requiring a lot of artistic editing and recoloring to make it even tolerable. Sometimes it seems like they take an image and say "how badly can we completely screw this up?", and then give it their best shot. Creating jagged lines through the image at which coloration goes completely nuts from one side to the other, putting an ugly red tint on the image, etc. Yet I never see these end results in Google Earth. Their imagery of the same area will be perfect.

I use a zoom of 12 before adding the map. The tutorial says he was able to use LOD 16 on his map selections, but I have never been able to achieve that consistently. I can get LOD15 for most US maps. For Canada it is anyone's guess - I've had very little luck with Canadian scenery. I've never tried any other country so don't know what you will see. But I guess the decision on what level of scenery detail you use will have to be personal choice combined with hardware in use. If I could consistently get higher resolution i think i could try to use it. But I might have to dial back the FSX settings a bit. It puts a heavier toll on the FPS count to fly helicopters, which I prefer. I've seen it drop as much as 50% compared to flying a plane. So I would likely see poor performance if I had been able to get LOD16 or higher scenery anyway. LOD 15 looks good from about 3000 feet AGL upward. What you will find is that the range of resolution offered for capturing the map is on a sliding scale tied to what zoom level you chose. If you do zoom in to say 13, you will see LOD17 and maybe 18 in the list. But whether you could succeed in getting it is another story. Conversely, if you zoom out to perhaps 10, you will see the LOD listings max out at like 10-12. But they do overlap a bit, meaning you can get a specific LOD map by using more than one zoom setting, I think. On my rig, if I zoom in past 13 SBX often will crash. So I try to carefully not exceed 12-13 when I am setting up to grab a map. I'd love to see some of your Austria scenery. :)

Generally, the order the scenery is listed will be the precedence it takes. So if you happen to be obscuring something on purpose, the obscured something would want to be lower on the list. However, unless you run into problems, I just keep adding the ones I create and not worry about their order. FSX will add to the top of the list when you add a new item. I have seen some retail scenery vendors specify the order their files should be with regard to some of the default FSX scenery. But for the most part I have not seen many problems. On the rare occasion something I have created seems to be getting covered over by default scenery, or by something else I had made earlier, I just move the covered over scenery higher on the list, and it fixes the problem. If you want a nice Crosshair Tool, I like the FinneyGround Crosshairs_Plus placement tool pack. You can get it here, compliments of Jim Robinson: http://www.cat-tamer.com/flightsim/d...hairs_Plus.zip The readme file talks about FS9 but it works just fine for FSX. There a couple variations in the crosshair appearance that install in your aircraft listings, and if you take it out of Slew mode while using one of them, you can actually fly the thing like a jetpack (complete with sound). :) I agree this is an awesome tutorial. Before I found this, originally given to us by Tiberius K., I had no idea how to make this scenery and had thought that it was a lot harder than it really is. There are a lot of steps, but once you do some over and over the steps fall into sequence in your mind, and you find it is easier. Plus not all of the steps in the original tutorial must be used, or you can add some of your own, like I do with the shoreline gradient, water coloration both for uniformity, and for effects like stained or muddy river water, and incorporating the incredible beauty of the various glacial sand formations around the Great Lakes shoreline areas. I have a lot of enjoyment from the project I started when I read this tutorial for the first time. It surprises me that FSX still has such a following. I think Microsoft was wrong to dismantle the FSX team. Clearly with the following FSX has they could have moved forward and had a lucrative market with future versions, rather than branching off into MS Flight, which is so very different I doubt it is appealing to us. I know I don't care for it.

Are you using Windows 7? There is a known "crash to desktop" issue in FSX with Windows 7. There is a patch you can download that will help a lot. Next time you see a bluescreen (technical name is a Windows STOP Error), if you can tell me exactly what the screen says I may be able to help you sort it out. But we should probably PM for that, and not post it in this thread. Also if you try searching this forum you may find a solution. When you want to do an island or land mass that is too big to fit in SBX, you need to do sections one at a time. Name each one uniquely so FSX doesn't think it is a duplicate entry. A word of caution here. In the Tools/Work subfolder of where you have SBX installed, where you go to get the files to use in the section of the tutorial regarding GIMP, SBX will OVERWRITE those files every time you start a new project. So I archive each file set in a folder elsewhere, naming the folder whatever I had named the scenery block the files were used to create. I also keep a dummy text file of that same name within the tools/work folder, which tells me which block the files are for, because SBX uses those long cryptic filenames which are meaningless, as well as repeatedly using names like Photo1.BGL for every new project. If you do not archive those files elsewhere, and you start the next SBX project, and capture a map, those files will be gone forever, permanently overwritten. If you later need to go back into SBX to edit or fix something you had not seen at first, say a misplaced edge of a hydropoly that causes default terrain to appear in your scenery, you will not be able to do so, and will have to completely begin from scratch and do the area again. By saving those files each time you finish a project in SBX, you can take any one of the saved sets of files, copy them to the tools/work folder, and then re-open that project in SBX. (All learned the hard way.) I have evolved to use the Crosshair Tool (downloadable as an addon aircraft) and I keep FSX running in Slew mode, looking down from above in the global external view. I then place the "aircraft" crosshair tool at the corner of an area I want to capture in SBX. FSX will actually do a very good job of overlapping and blending in adjacent scenery areas (often called blocks) but I like to slightly overlap them as a precautionary measure, because I have seen when 2 of my blocks ended up with a narrow strip of default scenery between them (after processing the added block for several hours) requiring me to have to start over. I really don't like doing a job twice. ;) So once you placed the crosshair, or plane you are using for a crosshair, at the corner of a new area to capture, use the SBX View menu to select Show Airplane. (BTW, this presumes you have FSUIPC up and running so FSX can talk to SBX.) Then click on Show Background. You can also work using Lat Lon coordinates, but if you want to do that you'll need to change settings in FSX, SBX, and (if you are using it) Google Earth so they all use the same format. I use decimal coordinates in all 3 applications and it works well. It can make locating an area in SBX easy, as you can enter the coordinates in the View menu and it will put you there. But I think using the Show Plane method has been faster than using coordinates. Now comes the difficult part. When you Add Map from background, you are familiar with how small the window is. Easy enough if you are selecting an entire tiny island like Nauru. To help select a piece of something larger, there are gridlines. Make use of those whenever you can, as it makes things much easier. But sometimes you can't use them. The only solution I have found is to single out definitive shapes on the land mass in the background view, and then find them in the smaller map window to use as a guide to selecting what I want. A city, farm field with a unique shape or color, the intersection of highways, etc. It would be really nice to have the little red crosshair appear on the Add Map window, but it doesn't. One reason the gridlines might not be optimal would be if you are trying to avoid creating the edge of your map parallel to and close to a shoreline. When you use shoreline gradients for shallower water, as I do, it creates headaches trying to match things up if the gradient runs against the edge of the scenery block image. I try to keep the selected map edges perpendicular to shorelines as much as possible. Selecting a map area 75% or less of the Add Map window usually goes more smoothly. Oddly, I have encountered situations where, at a specific geographical area, I was forced to use small sections of the Add Map window. Doing anything larger crashed SBX repeatedly. When I got away from that area by perhaps 50 miles, the problem went away, and I could actually select the whole Add Map window. (2200 cells at QMID 15 ... I have never been able to use QMID 16 as this tutorial suggests. The process always goes awry.) You'll probably find that the larger an area in the Add Map window you select, the more likely you will have problems with SBX getting quirky.....downloading all but the last 1 or 2 tiles, etc., requiring you to cancel, hide background, show background, etc. or even have to restart SBX entirely. It usually gives me fits at the beginning of a session, and then settles down after I have been working for awhile. I've seen a few times I had to reload SBX repeatedly (like 5 times) hiding and showing the background, etc. until it finally coughed up the image. Other times it runs smoothly with no problems. Kind of strange. Somewhere in this thread it is mentioned you can use TMFViewer (a tool provided in the FSX SDK files) to look at a BGL. It will also allow you to drag multiple BGL files dropped onto it, and will show you how they fit together. It is handy if you happen to get confused on which block you created goes where in FSX. I try to name the blocks after the nearest city name, since those are usually unique to an area. When I tried to use the names of lakes, I found out in Michigan there may be lots of lakes all over the state with identical names! So that doesn't work too well. :) We do have cities with the same names in multiple states here in the US though, so I began appending the state abbreviation onto the city name, like Detroit_MI. Anyway, if you are worried adjacent sections of an island might not overlap, once you have the BGL files from SBX for both sections, you can drag them onto TMFViewer to make sure they match up before moving on to the GIMP and Resample.exe compiling steps. I set Windows on my PC to automatically use TMFViewer to open .bgl files. So I can just click on the first BGL file to get TMFViewer open, then drag any additional BGL files onto the window. Sometimes it takes a while for TMFViewer to fully render the file. As long as they overlap a bit, FSX should be able to seamlessly assemble the island once you get all its sections loaded into the Scenery Library. :)

You're very welcome. I like sharing what I have learned. :) For areas without water, I experimented with what I learned here, and developed my own method. Resample.exe is expecting to find 3 bitmap files, as you have seen. It won't compile (as it is with the template INF file he uses for Nauru) without a a base image.bmp, watermask.bmp, and blendmask.bmp. So I do whatever processing I need for the base image (like the 10% contrast enhancement, any coloration fixes, etc.) and export that as the base image. Then create 2 new mask layers as you would normally do, named accordingly. But don't do anything else with them. They remain blank and fully transparent. Export each of them as you normally would. That way when you fill in the template INF file it still points to the required 3 bitmaps. Compile and you have your scenery BGL ready for placement. BUT..... There is a much faster way, if you are sure you don't need any changes made to the base image whatsoever. Make the map in SBX for the area and compile it normally. This always creates a file named Photo1.BGL. Copy that file to your Scenery folder for the area you are working on. Then, simply rename it to something relevant (whatever name you would have used in the full multi-step process). That's all you need do. Load the area into the Scenery Library as usual, refresh the scenery, and it will be there. In order to do the shoreline scenery for the Great Lakes area, AND make use of my purchased retail scenery for the inland areas, I had to determine which blocks of the retail scenery included any shoreline imagery, and remove them from the Scenery Library, while leaving the remaining inland blocks in use. I don't know what techniques this (now defunct) scenery vendor had used, but his scenery blocks (individual BGL files) are huge compared to what we can do in this tutorial. So once I culled all the shorelines and started creating my own blocks to fill them in, I had a lot of empty default scenery filling in the gaps. I had to work through all that as inland scenery just as I mentioned above. It goes pretty fast when GIMP is not involved at all. However, if you want to make any edits at all, you have to use the first of my 2 suggestions here. For example, if an inland lake or river is big enough that I want water effect rendered in it, I use the whole process complete with SBX hydro polys and populating both mask layers. If I just want to fix some coloration, I use blank mask layers and fix the base image. BTW, in case you haven't worked this out for yourself, I wanted to mention that a hydro poly in SBX does more than just tell FSX where to put water. It sets the elevation of the water, and in fact of the entire poly. So when doing water not at sea level, this is how you specify its surface elevation AND any beachhead it might have. If your area has sheer cliffs at the water edge, they poly line needs to be on the edge of the water, because FSX likely knows the elevations for that area and will render them accordingly. A hydro poly "overrides" the default elevation FSX wants to use. But if you have wide beach areas gently sloping into the water, draw the poly lines along the line where the beach ends and any land elevation increase takes place. It is often an artistic guess just where to draw the poly line with beaches. When in doubt I sort of split the difference between the water and land, along the middle of the beach. Google Earth is a very handy tool for finding elevations of land and surface elevations of inland water bodies. I use it a lot to determine what elevation (its in meters, not feet) to set the hydro poly when I draw one.

I ran across the description in the log file I keep on FSX describing how to reload scenery without having to restart FSX. The description is pretty straight forward, so I won't need pictures. All this assumes you have FSX up and running, maybe paused or in Slew mode while you are working on your scenery -- Adding scenery is never a problem, as FSX will automatically reload its scenery on the fly if you add a new area. But say you are replacing a BGL file with an updated version created from this tutorial, or also if you are placing scenery objects, editing an airport with ADE, etc. Maybe you saw a problem with a watermask once you loaded your custom scenery, and you had to re-compile the BGL file in that area's Scenery folder. You need to trigger FSX to refresh its scenery, but you don't want to wait through a shutdown and restart of FSX. All you need to do is open the FSX menu / World / Scenery Library. Select ANY ONE of the currently listed and active scenery files (I usually use whatever is at the top of the list). Un-check, then immediately Re-check the box next to that listing. Click OK in that window. FSX will reload the scenery and put you right back to whatever you were doing (flying, etc.) before you began this process. Now, say you are working with SBX and you need to enable some change you added, such as updating a polygon compiled CVX file, or maybe an exclude or waterclass. This part gets tricky, because FSX is USING the file as soon as you had put it into service and reloaded the scenery, per the above. Perhaps the exclude you tried did not work, and you want to remove it. Or maybe the waterclass color you selected doesn't match the surrounding water. Of course, you could use the Scenery Library to un-check that whole scenery area, but then you have to click OK and wait for the scenery reload, then remove the file you don't want in the Scenery folder, then re-check that scenery entry and click OK and wait again to reload the scenery again. But there is a much faster way! :) If you were to delete, say, an Exclude file from its Scenery folder while FSX is running, FSX will throw a hissy fit and start bombarding you with error messages endlessly because it is looking for the file and can't find it. Here is how to work around that: Go to the Flights menu and click End Flight (or press ESC). This brings up the End Flight dialog window. Leave that displayed, as it essentially puts FSX in limbo. Now delete whatever file you needed to delete from an active Scenery folder. Next, on the End Flight dialog window click Continue Flying. This will trigger FSX to reload its scenery as it resumes, and so it will no longer need the file you just deleted, and won't give you the error messages. :) I've done this dozens of times while working on scenery and not had a problem. It's really handy if you are trying to solve a problem with something in SBX and are not sure what kind of poly file you need to make to fix it, like if you have an anomaly in some water that requires experimentation. The first part of this info I read in a post on the FS Developer site. The second part I figured out through experimentation on my own. I hope you find it useful! :)

SBX isn't hard to use, although like GIMP it has its quirks. It sometimes doesn't like working with large areas, and will balk a bit, and the process to actually acquire a satellite image of any size is much like "babying" an old wheezing automobile, that has to be carefully tended with a lot of extra effort in order to get it to run. The procedure is kind of laughable. You have to go after an initial area (usually larger than what you really want), at which point it will download all but some varying number from 1 to 9 cells that refuse to download. Then you cancel out of the procedure, hide the background image, re-show the background image, and select the smaller area that you really want. Then you have a 50% shot it will download without at least one missing cell, causing you to have to start over. Or it may outright refuse to make the map, and you have to close SBX and start all over again. lol. I can do all that in my sleep now, just like the rest of the steps. You get used to it and just deal with its orneriness. :) What would be more of a concern for me would be whether you can actually get decent satellite imagery outside the US. Trying to get the Canada side of the Great Lakes is an exercise in futility. I managed to do "some" of it north of Lake Erie, but I definitely won't try more. It is almost like the satellite servers don't want you to use imagery outside the US. Like they are blocking access to it. You can find some of my posts here talking about it. That imagery is really bad. I prefer Virtual Earth as a server because it consistently gives me the best imagery. Regarding airstrips - Unless you want to add things or move them around for better realism, you won't have to edit every airport. I am only doing the ones I run across that have misplaced runways. FSX is bad for that. ADE has its own set of quirks, but I have managed to use it several times. It doesn't like large imagery though, so if I have an airstrip to work on I have to capture a small area just around the airstrip and use that bitmap. It will crash trying to use large bitmaps. Scruffy Duck recently told me he never designed it to work with large areas.

Congratulations! :) You memorized the process much faster than I did. I created a PDF copy of the thread, and used it as a guide countless times as I began my Great Lakes project, until I finally understood and remembered what each step does. Now if something goes wrong I can usually figure it out on my own (like for example having the base image accidentally selected along with the watermask when you export the watermask). The Adesso tablet comes with a pen, and together can replace the mouse in a lot of aspects. However, I very much prefer trackballs over mice, and I've been using them since they first became available. I can't justify using my whole arm to do something I can easily do with a slight thumb movement, including traversing all 3 of my displays in one pass of my thumb. Mice are limited to the size of their mousepad. Whereas a trackball can sit in one spot and give me pretty much limitless movement in any direction. That said, I use my trackball now to draw most of the things I need to draw, such as watermask borders around complex coastal areas. It just took me a while to get used to learn to draw with the trackball, but now that I can, it feels strange to try to use the tablet while watching the display, and the same issues of hitting the edge of the tablet are there, just like running out of mousepad. ;) So I don't use the Adesso much anymore unless I need to do something that I find difficult with the trackball. I looked back through this thread to see if I have already covered the FSX scenery reloading tips, and did not find nay reference to the method I use for loading scenery without an FSX restart. It would be best to include a few screen shots (a picture being worth a thousand words, as they say). So I'll create a different thread for it and post a link here when it is ready. :)

In your last photo, you've removed the wrong layer. You removed the blendmask layer, and left the base image layer, so you're seeing that because nothing else is left. In your second photo it appears you have both the blendmask and base image layer. (Don't make the mistake of drawing the watermask on the base image layer. ;) I always lock the base image layer immediately at the beginning of the process. If you decide to try my duplicate layer tip, unlock the duplicate, draw the white circle, and then re-lock it immediately, or if you are like me you will start drawing on it instead of the actual watermask layer. ;) GIMP is less than intuitive on how you move from layer to layer. I really wish there was a better method. It will actually let you work on a layer that is hidden, which I have done too many times! :) It took me awhile to get it through ny head that clicking on a layer only selects it, but does NOT make it visible, and similarly, making a layer visible by clicking on the eye icon does NOT also select that layer. As far as the little chain icon, I kept thinking that was what locked the layers, but found out I was wrong. Whatever it does, I never need it. I have to select the layer I want to lock, then click on the little brush icon at the top of the layers display. You can't tell if a layer is locked unless you select it. I don't like that. Each layer should always show if it is locked or unlocked all the time. ) I am quite happy to answer your questions whenever I can! :) Just keep in mind that I am not an expert at this, and some of the tricks I employ I got from others on this and other forums, and I have a tendency to prefer shortcuts when they will work. Speaking of, are you aware you can load new scenery without restarting FSX? Unless it crashes on me (rare, but it happens) I only start FSX once for the entire session, and leave it running while I work on, add, or edit scenery. There is even a way to remove scenery file that FSX is using, but it doesn't like it. You have to be quick and devious or you'll get a constant stream of error messages forcing you to restart FSX. Let me know if you want details on this aspect of the project. I don't want to stray from the scenery design technique discussion of this thread.

You're welcome! I don't know how detailed or how fast you are working, as there are a lot of variables to consider. I do this only for myself, so I opted to skip some things. I usually don't add shoreline wave effects, and I don't worry about the different seasons, or levels of scenery complexity, like one might do if making a retail product. I know what my preferences are, and what it takes to achieve them. You will find there is a practical limit to how large an area you can squeeze out of SBX, as it tends to choke when you try to use the entire area its map capture grid displays. I try to stay at 75% of that or less. Also when you do capture pretty much the whole 2200 cells in SBX, GIMP can get really bogged down working with the imagery. All that said, I can usually polish off an area from start to finish in a few hours. However you value your time, and however many of these SBX map sized areas there would be in Florida (a ton, I am guessing!) you're looking at a lot of hours to do it vs. that $20. BUT............ retail scenery often does not put the nice touches of detail on shorelines and harbors such as is my specialty. And in their attempt to unify the screwy colors we get fed from satellite imagery, sometimes the retail scenery uses a blueish shade of green for everything, which isn't very realistic. I guess it comes down to what you're happy with. I like doing this project because it is relaxing, oddly addictive for me, and lets me "fix" what I consider to be the totally butt UGLY shoreline imagery provided by sources like Google Earth, where they have the appalling "photo water" repeating ugly bands of color for miles from shore, which FSX will not render as water. The Great Lakes were just too ugly for me to tolerate in the scenery I bought myself, so I used this tutorial to learn to fix it, and ended up making all my own scenery now. I'm currently doing Upper Michigan, which I do not think is available as a retail product. Many of the shoreline glacial sand formations in this area are very cool, so I adopted a technique that allows them to be shown in the near shore shallows. Here's a handy tip for when you are using that fuzzy selection tool and working some detail in a small area, like trying to select boat docks. You will find when the colors you are selecting are matched closely by pixel colors in the water (happens a lot if the imagery has choppy water) trying to select will keep blowing out into the other nearby areas. Same thing happens on land selections too. What I do is make a duplicate copy of the base image layer, and work with the copy (hide the original, because you'll need it at the end). Say you are doing a marina harbor. Use the copied layer for all your selecting. Draw a nice wide (like 10 pixels wide) white line circle loosely around just the area in which you are working. It will prevent the Fuzzy Tool from wandering outside the circle. When you are done selecting and filling in the watermask selection, delete the copied layer of the base image, turn on your original base image layer, and move on to the next area. Or you can re-use the copied layer if the white circles you are drawing don't intersect each other. Between that tip and using the mouse wheel to increase/decrease the fuzzy tool selection sensitivity, you can select some things that might otherwise seem impossible. It also restricts the size of the selection area, which makes Gimp respond faster on larger images. So on detailed shorelines with lots of docks and convolutions, I'll work the shoreline in segments using those white circles to contain the size of the selected water area.