Comparison - DCW, VMAP0 Shorelines and GYM's Mapping Opportunity

Shoreline Map Comparison - Yahoo, Google, MS and EVS Precison

Shoreline Map Comparison - DCW and VMAP0

This post shows that Google Maps, Yahoo Maps and MS Live Search Maps use DCW/VMAP0 global shorelines for their mapping, at least in the area of Rabul. That is 1:1,000,000 scale global map coverage. James Fee, a well-respected GIS professional, commented, "When it comes to precision, I think the efforts for GYM (Google, Yahoo, Microsoft) should be on the navigation/geocoding/routing and not shorelines." First, one must agree with James' statement that GYM's maps are intended primarily for navigation/geocoding/routing. I believe that their customers, global in reach, would subject GYM's maps to many other GIS uses beyond navigation/geocoding/routing. I know that there is an agressive effort within the GIS community to provide a richer, more powerful set of tools, allowing any of us the opportunity to explore more complex spatial issues using Google Maps and Google Earth as platforms of choice. Ultimately, the end user, faced with a spatial problem requiring small scale maps would either have to make their own map, pay to have a map made, use a substandard map in place or not use a map at all.

In addition, James seems to suggest that 1:1,000,000 scale is satisfactory for GYMs primary efforts of navigation/geocoding/routing. I understand his reasoning, but I disagree. Before teaching, I did extensive geocoding of environmental risks. Locational precision was critically important. 1:1,000,000 was an unworkable geocoding scale. To follow the flight path of an enemy aircraft using 1:1,000,000 is doable. However, to locate enironmental risks at that large of a scale is asking for problems. A misplotted environmental risk could well result in a lawsuit. Business locations was another area I worked in and locational precision determined an exclusive market and was a contractual promise to the franchisee.

James goes on to say, "For me the shorelines are somewhat irrelevant to the routing provided. If I do need good shorelines, I'll probably just be using the aerial imagery in the first place." Again, his reasoning seems to make sense, but I disagree. First, shorelines are not somewhat irrelevant, they are a dynamic boundary between man and water. A raster image of a shoreline is practical for some applications, but a vector defined shoreline offer one a wide range of mapping possibilities. If I am GYM's map guru, I want my customers to have the greatest mapping precision possible. I don't want to impose precision limitations when there is no need. EVS precision shorelines, on a global scale, requires money to fund the mapping effort and time to complete the project. It will be money well spent. The resulting shorelines and other feature/land use layers will allow the "G", the "Y" or the "M" to be the number one mapping destination for all users and that could generate lots of ad dollars.

Finally, vector maps allow for infinite zooming with no lose of detail. If the initial vectors are created from quality base imagery (i.e., Landsat ETM+) and the map customers are able to easily access these detailed vector maps, they can tackle complex spatial issues using GYM's hi-precision mapping. Thus a marketing boon to the company savy enough to provide the product.

Enjoy!

P.S. - After yesterday's post, I received a query from an individual about EVS precision mapping for a section of Canadian shoreline. He had used WVS/GHHS vectors and they were unsatisfactory for his project. I sent him NGA PGS vectors covering his target area. They looked okay at 1:250,000 scale. He loaded them and acknowledged they were a significant improvement over the WVS/GHHS vectors, but were angular and did not track a cloud-free shoreline as one would expect. I created EVS precision vectors for him. He compared them to NGA PGS vectors and immediately acknowledged their higher quality. He asked if I would go ahead and create EVS precision vectors for his entire study area. I will, but wouldn't it have been cool for him to go to one of the big three mapping portals and find this mapping not only available, but downloadable? I think so.

How To Digitize Cloud-Obscured Shorelines

Raivava'e Atoll - EVS Precision Map on Landsat S-06-20_2000 (1-55,000)

As most of my regular readers know, the bulk of my mapping work is derived from Landsat ETM+. My primary reason for using Landsat ETM+ as base imagery is consistency of product. Typically, anywhere on earth this imagery is freely available, virtually cloud-free and consistently resolved to 14.5-meters per pixel. Great for my worldwide island mapping work. Plus, there are minimal copyright issues when using this imagery. All that is asked is that you credit the source imagery. Did I say "virtually cloud-free"? That is everywhere but in humid climates, in other words in and around islands. Oh, well, it is merely a challenge that the accomplished mapper learns to work around.

The above image is an example of cloud-obscured island imagery. Most of Raivava'e Atoll is visible, but those areas not visible are significant. How does one resolve these areas using copyright-free data (credit source data)? If I am unable to secure Landsat 1990 imagery, which quite often enables one to resolve cloud-obscured areas, I go to Shuttle photography. Specifically, searching for ISS (International Space Station) imagery.

Raivava'e Atoll - EVS Precision Map on ISD_ISS001-375-13 Modified (1-55,000)

Raivava'e Atoll has two images that show the atoll with virtually no clouds. These images are sufficiently large enough that one is able to zoom into and digitize features. First, however, the ISS image must be georectified. Global Mapper allows me to georectify ISS imagery using my Landsat base imagery. In georectifying this ISS image, I used 7 GCP's to ensure the ISS image lay precisely on top of the Landsat base image.

Raivava'e Atoll Outlying Motus - EVS Precision Map on Landsat S-06-20_2000 (1-10,000)

Raivava'e Atoll Outlying Motus - EVS Precision Map on ISD_ISS001-375-13 Modified (1-10,000)

Beginning with the cloud-obscured Landsat image above, I digitized as much of the atoll as possible. The cloud-obscured portions were identified and designated for further work. Visiting Shuttle photography, I found 2 cloud-free images of Raivava'e Atoll. I selected ISD_ISS001-375-13 as the better of the two images. I rotated it and cropped to the atoll. Using this modified ISS image, I was able to complete digitizing the cloud-obscured shoreline. When all else fails, I use WVS shorelines. They are crude compared to EVS precision, but they work.

I use red shorelines to designate EVS precision derived from Landsat base imagery. The green shorelines are designated as Other precision. The source for all Other precision shorelines in my Raivava'e Atoll map is the ISS imagery.

My EVS precision island map of Raivava'e Atoll is complete and I was able to digitize all shorelines in spite of clouds. Pretty cool, huh?

Enjoy!

Thoughts - Mapping New Britain PP

I was explaining my mapping work to a person I met at a party earlier today. This individual asked all of the right questions ( What do you do? Where do you get your images? How do you digitize the shorelines? What do you do with your finished maps?) Poor guy! I answered every question with a detailed, lengthy and somewhat technically boring response. After my fifth lengthy reply, he excused himself and joined another group.

As I reflect on my exchange with this curious person, I am amazed at the breadth of my knowledge and convinced that I can be very boring. I really do know quite abit about digitizing shorelines. After a few thousand kilometers of continental shorelines and 9,000 island shorelines, I am able to digitize a precise shoreline (within the limitations of Landsat ETM+'s 14.5-meter resolution).

Early on, I had professional cartographers tell me my maps would be useful at 1:125,000 to 1:63,500. I have learned that my island shoreline maps are useful at scales well-below these upper limits. I typically post completed maps at 1:25,000 scale. After adding layers of information, they work well for an individual attempting to determine a relatively coarse view of an island. Landsat is not DigitalGlobe's hi-res imagery, but it does a great job at giving one a highly resolved broad view of a geographical area.

New Britain PP - Digitizing from Landsat S-55-05_2000 (1:19960)

So, how is it that I do what I do? In digitizing, that is. The above image shows a typical stretch of large island shoreline. An attempt to generate vector shorelines from Landsat ETM+ was done a few years ago. This data, called NGA PGS, is fairly good at defining a shoreline, but coastal swamps are excluded causing some very strange looking maps of islands. If the island or shoreline contains water-innundated shoreline, NGA PGS does not map it. They could have, but someone, somewhere thought it would be good to exclude it. My shorelines include these water-innundated areas. The red line in the above image is my completed EVS precision shoreline. Except for the final vector which I purposely placed in the sea, the shoreline is much more accurately delineated than NGA PGS, WVS, DCW or any of the other available global shorelines. I am not saying EVS precision shorelines are global yet. I am an optimist. Someone, somewhere, sooner than later will fund my mapping efforts and the result will be a global shoreline at EVS precision.

Enjoy!

Thoughts - FLASH! 8,000 Pacific Islands Mapped at EVS Precision

EPIP - Pacific Islands Overview

The 8,000 islands located in the following island groups: Papua New Guinea, Solomon Islands, Vanuatu, Fiji, Cook Islands, Western Samoa, Tonga and portions of Kiribati were mapped at EVS precision. Using Landsat ETM+ ortorectified image mosaics, which typically resolve to 14.5 meters per pixel as base imagery, Mr Minton spent in excess of 240-hours over 31-days digitizing, correcting and finalizing island shorelines throughout this region of the Pacific. Mr Minton used a variety of strategies to resolve cloud-obscured shorelines. Those that ultimately could not be resolved were mapped using World Vector shorelines. This impressive effort is being fine tuned using 1990 Landsat imagery, when available.

You heard it right! I spent the last month mapping thousands of islands at EVS precision. I did get paid to do it. Part of me wants to rest, as I sure deserve it. However, the island mapper in me demands that I resolve problem areas, primarily cloud-obscured areas, by correcting island shorelines using cloud-free imagery.

If you are interested in these shorelines, email me and let's talk.

Finally, I will finish mapping the balance of the Pacific islands at EVS precision. Stay tuned for updates on this effort.

Enjoy!

Comparison - EVS to NGA PGS, One More Time

Kyra Panagia - EVS Compared to NGA PGS

Enhanced Vector Shorelines are derived from Landsat ETM+ mosaics. When I carefully digitize an island shoreline using Landsat imagery as my base image, I create EVS precision vectors. This name describes an improved shoreline over World Vector Shorelines.

The NGA Prototype Global Shoreline claims to be a global vector shoreline derived from Landsat ETM+ mosaics, the same imagery I use. When I first learned of it, I thought to myself, "My work is done! MDA has produced the ultimate global vector shoreline. Well, they really haven't. It seems that their shorelines do not track Landsat's imaged shorelines. They are close, somettimes very close. But far too often, they are off, sometimes by 100's of feet.

It is my contention, if Landsat provides a clearly imaged shoreline, the vectors that describe that shoreline should be as close to the shoreline as possible. NGA PGS does a pretty good job, but when I compare their product to my EVS precision shorelines - mine are better at tracking the Landsat imaged shoreline.

Enjoy!

Thoughts - EVS Precision Digitizing at 2-Kilometers per Minute

Nisida Ioura - LIIM From N-34-35_2000 (1:65,000)

So you've always wanted to hand-digitize an island shoreline. Your GIS friends tell you "No way! It takes way too long. And it's not as accurate as some of these slick black-box vectorizing software packages." You ignore them. Good for you!

First get you a good software package to digitize from. You all know where I stand - Global Mapper. You can always download and try their software for free. Just select my Global Mapper sidebar link and follow the instructions. Once you've got the mapping software loaded, it is time to get your base imagery. You can either download it from the NASA site or get in touch with me and I'll hook you up with imagery for your island.

Nisida Ioura - EVS Precision and GSHHS WVS (1:65,000)

Load the imagery into GM, zoom into a section of the shoreline where you will begin digitizing at a scale of 1:12,500, switch on Anti-Alias option in the Control Panel for your base image, select the digitizing tool, select the "Draw a Line" option and start digitizing. I like digitizing to music. This morning it was "The Planets" by Gustav Holst. I traced the above island's shoreline, listened to music and sipped a cup of coffee. I started at 5:50AM and finished Nisida Ioura's shoreline at 6:05AM - 15-minutes to digitize a perimeter of 30-kilometers - 2-kilometers per minute.

I always experience a satisfying sense of accomplishment when I complete an island's shoreline at EVS precision. I know that my island shorelines are as accurate as one can get using the tools I use. I have done enough comparisons to know that my shorelines can be used to create useful maps suitable for a wide range of activities.

If you want to make your own maps, just do it. Stop making excuses. Stop letting others tell you what you can or can't do. Go ahead and make your map. If your first one looks crappy, I promise your next one will look less crappy. And after a few years of making your own maps - you'll be able to say "Now, that's a nice map!"

Enjoy!

Comparison - WVS, SWBD, NGA PGS Global Shorelines and EVS Precision Shorelines

Three Vector Shoreline's Compared - WVS, SWBD and EVS Precision

One of my readers suggested I evaluate SWBD shorelines in comparison to other freely available shorelines. Previously, I compared these shorelines with my own EVS precision shoreline. I'll do it once more.

The WVS is widely available and manageable in size. There is another popular version of it called the GSHHS. It repairs varous WVS anamolies. In addition, it conveniently breaks the dataset into land, lakes, ponds and islands. At only 56MBs zipped, it is a very attractive option. As one can see in the two images, the WVS is the least precise of all large scale global shorelines. It is designed to be used at scales of 1:250,000 and above. For most of us designing projects for our classroom, employers or customers, this dataset does a fine job, it is free and the size is reasonable. It is when we need to do large scale precise shorelines that we require the next best global shorelines

Although the SWBD is a quality product and provides the end-user with precise SRTM water-defined shorelines, it tracks the water. The SWBD attempts to identify the place where the water meets the shore. That should be the shoreline, but it isn't. The top image shows the SWBD shoreline tracking the reef edges and ignoring the numerous motus within the reef. For us island mappers, the SWBD is not precise enough to identify the many shoreline features we require.

The same can be said for the NGA PGS shorelines. They are extremely precise, using Landsat ETM+ imagery as their base imagery. This is the same imagery I use to construct my EVS precision maps. I have the NGA PGS shoreline loaded into Marplot, a mapping package I use. The dataset is divided into 24 separate groups. My global coverage, using this dataset, is outstanding - except where clouds or other atmospherics obscure the shoreline or the shoreline consists of water-inundated areas (marsh, swamp, mudflats), which the NGA PGS product didn't identify. The cloud obscured areas on Landsat ETM+ imagery are validly poorly mappable to unmappable. The water-inundated areas are mappable, but the NGA contract called for the exclusion of these shoreline features, thus they were not mapped. I beg to differ. This is shoreline that must be mapped. There are massive river deltas NGA PGS mapped that depict shorelines that look nothing like the original Landsat ETM+ image, which is full of features that the NGA PGS product did not map. They just happen to be water-inundated. They are features you and I would describe as shoreline. Make no mistake, when the shoreline is cloud-free and not water-inundated, which most Landsat imaged shorelines are, this global shoreline dataset is outstanding. It's just all of those river delta islands that they didn't map that I have a problem with.

Four Vector Shoreline's Compared

However, my EVS precision shorelines are pretty outstanding as well. When one compares my hand-drawn shorelines to programmed color tracking shorelines (or many other automated processes), my hand-drawn shorelines track quite precisely. Something about using one's brain processing powers, manual dexterity and years of experience that consistently allows one to create more precise shorelines than the WVS, SWBD and NGA PGS products.

As I work with Landsat ETM+ imagery and learn more about the digitizing craft, I am certain software is available that could do what I do more accurately, faster and in much less time. But it wouldn't be as much fun! Would it?

Enjoy!

Comparison - Haifa Harbor Using 1:2000000, 1:250000, NGA PGS and EEVS Precision Shorelines

Haifa Harbor - DigitalGlobe Image from Google Earth (1:4,600)

Let's begin this comparison of shoreline accuracy by superimposing four shorelines onto a 1-meter resolution image of Haifa Harbor. Why Haifa? Just because I happened to be making a land-sea mask in this part of the world. My initial study focused on using NGA's Prototype Global Shorelines (PGS) created from Landsat ETM+ imagery. As you will read and see this global shoreline is one of the most detailed available. It does have a few negative considerations, like "stuttering" shorelines, non-mapping of water-inundated land (swamps, marshes, etc.) and hand-tracing of shorelines is more accurate than the software generated shorelines...but, that said, NGA PGS shoreline is a great first-step toward a global shoreline for all of us.

Haifa Harbor - 1:2,000,000 (Red) and 1:250,000 (Blue) (1:4,600)

The 1:2,000,000 (Red) shoreline is, by virtue of it's name, designed to be used at 1:2,000,000 or smaller resolutions. It works well for coarse shoreline delineation to get "an idea" of where the shore ends and the sea begins. The 1:250,000 goes by the acronym W(orld) V(ector) S(horelines). It was originally extracted from Tactical Pilotage Charts. It gives one a useful shoreline for a wide variety of projects. However, when one pushes it beyond 1:250,000 it quickly proves inaccurate in tracing the actual shoreline.

Haifa Harbor - NGA PGS (Yellow) and EEVS Precision (Lite Blue) (1:4,600)

Now for the good stuff! The NGA PGS precision shorelines do a fairly good job of tracking the actual shoreline. They are deemed appropriate at scales between 1:125,000 to 1:250,000. Some areas could be pushed to 1:62,500, but be careful. I am careful and I push them below 1:62,500, for digitizing purposes, in order to confirm my Landsat derived hand-made vectors are of greater precision than the PGS. And mine are! For the purposes of this comparison the PGS shorelines would give a person an accurate shoreline impression as long as it was not superimposed over the actual shoreline. The lite blue line is what I call E(xtremely) E(nhanced) V(ector) S(horelines). They are derived from DigitalGlobe's 1-meter resolution imagery found in Google Earth. Oh, that all the world were imaged at 1-meter cloud-free resolution. I feel that is a long way coming and I don't think the global shoreline vector files derived from them will be free. I suspect they will be quite costly.

Back to the land-sea mask, or what started this current study. The most accurate vector based global land-sea mask is mine. I call it GSHHS Derived Global Land-Sea Mask and you can download a copy here. Be forewarned, the file is 83.9MBs zipped and 340MBs unzipped.

The most accurate future global shoreline map should be the NGA PGS precision product, but it needs work to finish it (correct stutters, map non-mapped areas, etc.). Once it is finished, it will be THE GLOBAL SHORELINE. Until then, WVS rules.

Enjoy!

Data - Global Land Mask using Vectors instead of 1-Kilometer Grid Cells

Global Land Mask using GSHHS Modified WVS

Regular readers know that I am a long time user of World Vector Shorelines (WVS). These vectors cover the world at a scale of 1:250,000. If you download them, you will see that they are not polygons, but line files. I have always wanted to create a land-mask of all land areas within this database, but have never had the time, software or computer calculating power. That was until yesterday. A reader asked if I knew whether their was a land-sea mask at better resolution then the 1-kilometer grid cell version currently available. To tell the truth, I didn't know about land-sea mask maps. After a brief search of some of my sources I found out that the main global land-sea mask was something build back in 1996 using WVS. Instead of using vectors as the deliverable, the builder fashioned the 1-kilometer grid map.

I let my reader know that the 1-kilometer global land-sea mask he currently was using was, probably, the best going. He knew of the Globcover LULC 300-meter grid cell version coming out in the first part of February 2008 to be created and made available by ESA.

Global Land Mask - Eastern Canada and US

Curious soul that I am and having time, software and computer capabilities, I decided I would create my own global land mask. I loaded the land files taken from GSHHS, a modified version of WVS, into Global Mapper. Using a simple routine within the digitizing tools, I created polygons from lines. Simple process, but very long processing time. Eurasia took over 4-hours to process. After working at it all day and night, I came up with my vector version of a Global Land Mask. The entire file is 340MBs in size (84MBs zipped). It takes about 3-minutes to load into GM, but wow! It does look pretty cool.

Global Land Mask - San Diego with 1-kilometer grid cell (1-125,000)

The above image is at a scale of 1:125,000 (1-inch to 2-miles). The 1-kilometer grid cell is placed on the map to give you an idea of the coarseness one gets using the existing global 1-kilometer grid-cell map. Even though it was derived from WVS vectors, not using the power of vectors (infinite zooming capabilities) one encounters an unnecessary coarseness not evident in the vector-based product.

I think my vector-based product is an example of a wonderful land-sea mask.

Enjoy!

Thoughts - Marplot, A Beginner's Mapping Package

Europe - WVS Marplot Map (1:392 km)

I do much of my mapping using Marplot. This free, tax-payer-dollars-funded mapping program was initially designed to help environmental emergency responders detail their findings. NOAA also did work with the software, not sure what they did, but they did it. With the advent and purchase of robust, powerful, complex and expensive mapping packages, the government use of this product is shrinking. Their serious mapping efforts are handled by the ARC GIS mapping packages and some MapInfo. But Marplot still exists and the price is right - free!

The learning curve for this mapping package is fast. The ability to compile multiple layers of information and control their symbol, color, range, line-width, and fill is nice. My World Shoreline database is made up of 200-plus layers of information. The mapping capabilities will frustrate the seasoned mapper, but for us rookies, it is a great, free option.

Using a freeware program called shp2mie any shapefile can be quickly converted into Marplot's mie format. This really opens up a world of mapping opportunities. Every map I construct is worked on in Marplot. Every database I encounter, ultimately is reformatted so that I can import it into Marplot. It is a mapping package that allows the neophyte mapper to try their hand at the mapping art with minimal frustration.

I have lots of data in Marplot's mie format. In fact too much to list. If you have your own unique dataset, I could reformat it to work in Marplot.

I am discussing this mapping package and it's capabilities, because this site gets a number of inquiries about Marplot compatible data files. I know the US county-level TIGER files will import directly into Marplot, but almost all other data needs to be reformatted. My favorite reformatting package is Global Mapper. It handles almost every type of mapping format and converts them easily to a Marplot compatible format. If you have questions specific to Marplot capabilities, I'll be glad to try and answer them for you. It is a solid beginner mapping package. Give it a try.

Enjoy!

Data - WVS/GSHHS Global Shorelines

WVS/GSHHS - Pacific Centered

Over three years ago I learned of the GSHHS vector map file of the world shorelines. The data is reworked WVS, which allows one to construct a 1:250,000 world map. My problem was the only mapping software I used at the time was Marplot. Unfortunately, Marplot is quite limited in files that can be imported into it. So I held this data until I purchased software that could read and display the data. Along came Global Mapper.

WVS/GSHHS - Atlantic Centered

WVS/GSHHS - Atlantic Centered without Inland Water Features

I did not want to work with a Pacific-centered map. The version of the GSHHS only came as a Pacific-centered map. I prefer working with Atlantic-centered map. So I asked Mike, at Global Mapper, if he could modify the file into an Atlantic-centered map file. He said sure, and he did it that same day. This map I could use. I loaded the files into Marplot and used them extensively as a primary global shoreline. But somebody stuffed a batch of water features into this database. So, for the past 4-hours I carefully removed, named and relayered these inland water features.

GSHHS - Atlantic Centered with Inland Water Features Modified

WVS/GSHHS - Atlantic Centered with Inland Water Features; Detail Caspian Sea

WVS/GSHHS - Atlantic Centered with Inland Water Features and Streams; Detail Caspian Sea

After removing these inland water features from the WVS/GSHHS data set, I converted them into polygons and placed them back into the WVS/GSHHS map. I then inserted the VMap0 stream/river/intermittent stream line file which I had extracted from VMap earlier. The final map above shows the Caspian Sea with all of the streams that feed into it.

What prompted me to go through this exercise, was the four or five readers every day that come to this website looking for world shorelines. The WVS/GSHHS data is excellent. It allows one to plot a highly accurate view of the world. Using the NGDC Coastline Extractor one can download various layers of boundary information, along with the global shorelines.

It turns out that the GSHHS data is now available as an Atlantic-centered map with all of the inland water features bundled with the primary shoreline data as additional layers of information. And the price is FREE!

I really like the WVS/GSHHS data. Once loaded, it gives one an excellent shoreline resource. What you need after loading the WVS/GSHHS data is the VMap0 data layers (Roads, Railroads, Contours, Depth Contours, streams, lakes, etc.). Then you have a very slick map to work with.

Enjoy!

Comparison - EVS-R and WVS

World Vector Shorelines (WVS) is the default shoreline for most government produced maps. It is also used extensively by many in the commercial mapping arena to produce their products. It is an excellent vector map file that shows shorelines of the world in exquisite detail.

That said, I searched for a detailed map of the Tokelau Islands at a large enough scale that all three of the atolls (Atafu, Nukunonu and Fakaofo) could be displayed.

Google Image Search Results - Tokelau Map

Every readily available map used the same data source for their shorelines - WVS. The best scale to display all three atolls is 1:750,000. I thought that WVS would be the ideal source - Wrong! Knowing what I know about atoll shapes and the importance of including the reef as part of the shoreline, WVS was woefully inadequate.

The answer was simple - merely create a new vector file of these three atolls. Using Global Mapper and Landsat ETM+ as base imagery, I worked at a scale of 1:62,750 and digitized the land areas and reefs of these three atolls. Using Marplot I created this new layer of mapping information called Enhanced Vector Shoreline-Rough (EVS-R).

EVS-R and WVS (1-1,000,000)

EVS-R and WVS (1-250,000)

Not only is the EVS-R a more detailed image, but it is accurately plotted at this scale. You will notice that the WVS is misplotted further north than it should be.

It is a major improvement over WVS. What do you think?

Enjoy!