diff --git a/lib/CGameState.cpp b/lib/CGameState.cpp
index ef732ccbe..95e5090d4 100644
--- a/lib/CGameState.cpp
+++ b/lib/CGameState.cpp
@@ -746,6 +746,7 @@ void CGameState::init(StartInfo * si, bool allowSavingRandomMap)
 	buildBonusSystemTree();
 	initVisitingAndGarrisonedHeroes();
 	initFogOfWar();
+	initSightMap();
 
 	// Explicitly initialize static variables
 	for(auto & elem : players)
@@ -1512,6 +1513,55 @@ void CGameState::giveCampaignBonusToHero(CGHeroInstance * hero)
 	}
 }
 
+void CGameState::removeSightnObj(const CGObjectInstance * obj)
+{
+	addSightObj(obj, false);
+}
+
+void CGameState::addSightObj(const CGObjectInstance * obj, bool add)
+{
+	if(!vstd::contains(players, obj->tempOwner))
+		return;
+
+	auto p = getPlayer(obj->tempOwner);
+	if(p->status != EPlayerStatus::INGAME)
+		return;
+
+	addSightObj(p->team, obj, add);
+}
+
+void CGameState::addSightObj(TeamID team, const CGObjectInstance * obj, bool add)
+{
+	auto ts = getTeam(team);
+	std::unordered_set<int3, ShashInt3> tiles;
+	getTilesInRange(tiles, obj->getSightCenter(), obj->getSightRadius());
+	for(int3 t : tiles)
+	{
+		if(add)
+		{
+			if(ts->fogOfWarMap[t.x][t.y][t.z] == 0)
+				ts->fogOfWarMap[t.x][t.y][t.z] = 2;
+			else
+				ts->fogOfWarMap[t.x][t.y][t.z]++;
+		}
+		else
+		{
+			ts->fogOfWarMap[t.x][t.y][t.z]--;
+		}
+	}
+}
+
+void CGameState::initSightMap()
+{
+	for(CGObjectInstance * obj : map->objects)
+	{
+		if(!obj)
+			continue; //not a flagged object
+
+		addSightObj(obj);
+	}
+}
+
 void CGameState::initFogOfWar()
 {
 	logGlobal->debug("\tFog of war"); //FIXME: should be initialized after all bonuses are set
@@ -1529,18 +1579,6 @@ void CGameState::initFogOfWar()
 			for(int h=0; h<map->height; ++h)
 				for(int v = 0; v < (map->twoLevel ? 2 : 1); ++v)
 					elem.second.fogOfWarMap[g][h][v] = 0;
-
-		for(CGObjectInstance *obj : map->objects)
-		{
-			if(!obj || !vstd::contains(elem.second.players, obj->tempOwner)) continue; //not a flagged object
-
-			std::unordered_set<int3, ShashInt3> tiles;
-			getTilesInRange(tiles, obj->getSightCenter(), obj->getSightRadius(), obj->tempOwner, 1);
-			for(int3 tile : tiles)
-			{
-				elem.second.fogOfWarMap[tile.x][tile.y][tile.z] = 1;
-			}
-		}
 	}
 }
 
diff --git a/lib/CGameState.h b/lib/CGameState.h
index cc75984ce..556e1334f 100644
--- a/lib/CGameState.h
+++ b/lib/CGameState.h
@@ -178,6 +178,10 @@ public:
 	std::vector<CGObjectInstance*> guardingCreatures (int3 pos) const;
 	void updateRumor();
 
+	void initSightMap();
+	void addSightObj(const CGObjectInstance * obj, bool add = true);
+	void removeSightnObj(const CGObjectInstance * obj);
+
 	// ----- victory, loss condition checks -----
 
 	EVictoryLossCheckResult checkForVictoryAndLoss(PlayerColor player) const;
@@ -268,6 +272,7 @@ private:
 	void initStartingResources();
 	void initHeroes();
 	void giveCampaignBonusToHero(CGHeroInstance * hero);
+	void addSightObj(TeamID team, const CGObjectInstance * obj, bool add = true);
 	void initFogOfWar();
 	void initStartingBonus();
 	void initTowns();
diff --git a/lib/IGameCallback.cpp b/lib/IGameCallback.cpp
index 584ade005..6f0eb8615 100644
--- a/lib/IGameCallback.cpp
+++ b/lib/IGameCallback.cpp
@@ -78,8 +78,8 @@ void CPrivilagedInfoCallback::getTilesInRange(std::unordered_set<int3, ShashInt3
 				if(distance <= radious)
 				{
 					if(!player
-						|| (mode == 1  && team->fogOfWarMap[xd][yd][pos.z]==0)
-						|| (mode == -1 && team->fogOfWarMap[xd][yd][pos.z]==1)
+						|| (mode == 1  && team->fogOfWarMap[xd][yd][pos.z] == 0)
+						|| (mode == -1 && team->fogOfWarMap[xd][yd][pos.z] > 0)
 					)
 						tiles.insert(int3(xd,yd,pos.z));
 				}
diff --git a/lib/NetPacksLib.cpp b/lib/NetPacksLib.cpp
index 85a187bdf..68c0daafe 100644
--- a/lib/NetPacksLib.cpp
+++ b/lib/NetPacksLib.cpp
@@ -220,29 +220,13 @@ DLL_LINKAGE void FoWChange::applyGs(CGameState *gs)
 {
 	TeamState * team = gs->getPlayerTeam(player);
 	for(int3 t : tiles)
-		team->fogOfWarMap[t.x][t.y][t.z] = mode;
-	if (mode == 0) //do not hide too much
 	{
-		std::unordered_set<int3, ShashInt3> tilesRevealed;
-		for (auto & elem : gs->map->objects)
-		{
-			const CGObjectInstance *o = elem;
-			if (o)
-			{
-				switch(o->ID)
-				{
-				case Obj::HERO:
-				case Obj::MINE:
-				case Obj::TOWN:
-				case Obj::ABANDONED_MINE:
-					if(vstd::contains(team->players, o->tempOwner)) //check owned observators
-						gs->getTilesInRange(tilesRevealed, o->getSightCenter(), o->getSightRadius(), o->tempOwner, 1);
-					break;
-				}
-			}
-		}
-		for(int3 t : tilesRevealed) //probably not the most optimal solution ever
-			team->fogOfWarMap[t.x][t.y][t.z] = 1;
+		if(mode == 0 && team->fogOfWarMap[t.x][t.y][t.z] > 1)
+			continue;
+		else if(mode == 1 && team->fogOfWarMap[t.x][t.y][t.z])
+			continue;
+
+		team->fogOfWarMap[t.x][t.y][t.z] = mode;
 	}
 }
 
@@ -309,9 +293,11 @@ DLL_LINKAGE void ChangeObjPos::applyGs(CGameState *gs)
 		logNetwork->error("Wrong ChangeObjPos: object %d doesn't exist!", objid.getNum());
 		return;
 	}
+	gs->removeSightnObj(obj);
 	gs->map->removeBlockVisTiles(obj);
 	obj->pos = nPos;
 	gs->map->addBlockVisTiles(obj);
+	gs->addSightObj(obj);
 }
 
 DLL_LINKAGE void ChangeObjectVisitors::applyGs(CGameState *gs)
@@ -386,6 +372,7 @@ DLL_LINKAGE void RemoveObject::applyGs(CGameState *gs)
 	CGObjectInstance *obj = gs->getObjInstance(id);
 	logGlobal->debug("removing object id=%d; address=%x; name=%s", id, (intptr_t)obj, obj->getObjectName());
 	//unblock tiles
+	gs->removeSightnObj(obj);
 	gs->map->removeBlockVisTiles(obj);
 
 	if(obj->ID==Obj::HERO)
@@ -516,6 +503,8 @@ void TryMoveHero::applyGs(CGameState *gs)
 		logGlobal->error("Attempt ot move unavailable hero %d", id.getNum());
 		return;
 	}
+	if(start != end)
+		gs->removeSightnObj(h);
 
 	h->movement = movePoints;
 
@@ -547,17 +536,19 @@ void TryMoveHero::applyGs(CGameState *gs)
 		h->boat = nullptr;
 	}
 
-	if(start!=end && (result == SUCCESS || result == TELEPORTATION || result == EMBARK || result == DISEMBARK))
+	if(start != end)
 	{
-		gs->map->removeBlockVisTiles(h);
-		h->pos = end;
-		if(CGBoat *b = const_cast<CGBoat *>(h->boat))
-			b->pos = end;
-		gs->map->addBlockVisTiles(h);
-	}
+		if(result == SUCCESS || result == TELEPORTATION || result == EMBARK || result == DISEMBARK)
+		{
+			gs->map->removeBlockVisTiles(h);
+			h->pos = end;
+			if(CGBoat *b = const_cast<CGBoat *>(h->boat))
+				b->pos = end;
+			gs->map->addBlockVisTiles(h);
+		}
 
-	for(int3 t : fowRevealed)
-		gs->getPlayerTeam(h->getOwner())->fogOfWarMap[t.x][t.y][t.z] = 1;
+		gs->addSightObj(h);
+	}
 }
 
 DLL_LINKAGE void NewStructures::applyGs(CGameState *gs)
@@ -571,7 +562,9 @@ DLL_LINKAGE void NewStructures::applyGs(CGameState *gs)
 		t->updateAppearance();
 	}
 	t->builded = builded;
+	gs->removeSightnObj(t);
 	t->recreateBuildingsBonuses();
+	gs->addSightObj(t);
 }
 DLL_LINKAGE void RazeStructures::applyGs(CGameState *gs)
 {
@@ -583,7 +576,9 @@ DLL_LINKAGE void RazeStructures::applyGs(CGameState *gs)
 		t->updateAppearance();
 	}
 	t->destroyed = destroyed; //yeaha
+	gs->removeSightnObj(t);
 	t->recreateBuildingsBonuses();
+	gs->addSightObj(t);
 }
 
 DLL_LINKAGE void SetAvailableCreatures::applyGs(CGameState *gs)
@@ -661,6 +656,7 @@ DLL_LINKAGE void HeroRecruited::applyGs(CGameState *gs)
 	{
 		t->setVisitingHero(h);
 	}
+	gs->addSightObj(h);
 }
 
 DLL_LINKAGE void GiveHero::applyGs(CGameState *gs)
@@ -720,6 +716,7 @@ DLL_LINKAGE void NewObject::applyGs(CGameState *gs)
 	gs->map->addBlockVisTiles(o);
 	o->initObj(gs->getRandomGenerator());
 	gs->map->calculateGuardingGreaturePositions();
+	gs->addSightObj(o);
 
 	logGlobal->debug("Added object id=%d; address=%x; name=%s", id, (intptr_t)o, o->getObjectName());
 }
@@ -1166,29 +1163,40 @@ DLL_LINKAGE void SetObjectProperty::applyGs(CGameState *gs)
 		return;
 	}
 
-	CArmedInstance *cai = dynamic_cast<CArmedInstance *>(obj);
-	if(what == ObjProperty::OWNER && cai)
+	if(what == ObjProperty::OWNER)
 	{
-		if(obj->ID == Obj::TOWN)
+		CArmedInstance *cai = dynamic_cast<CArmedInstance *>(obj);
+		if(cai)
 		{
-			CGTownInstance *t = static_cast<CGTownInstance*>(obj);
-			if(t->tempOwner < PlayerColor::PLAYER_LIMIT)
-				gs->getPlayer(t->tempOwner)->towns -= t;
-			if(val < PlayerColor::PLAYER_LIMIT_I)
+			if(obj->ID == Obj::TOWN)
 			{
-				PlayerState * p = gs->getPlayer(PlayerColor(val));
-				p->towns.push_back(t);
+				CGTownInstance *t = static_cast<CGTownInstance*>(obj);
+				if(t->tempOwner < PlayerColor::PLAYER_LIMIT)
+					gs->getPlayer(t->tempOwner)->towns -= t;
+				if(val < PlayerColor::PLAYER_LIMIT_I)
+				{
+					PlayerState * p = gs->getPlayer(PlayerColor(val));
+					p->towns.push_back(t);
 
-				//reset counter before NewTurn to avoid no town message if game loaded at turn when one already captured
-				if(p->daysWithoutCastle)
-					p->daysWithoutCastle = boost::none;
+					//reset counter before NewTurn to avoid no town message if game loaded at turn when one already captured
+					if(p->daysWithoutCastle)
+						p->daysWithoutCastle = boost::none;
+				}
 			}
-		}
 
-		CBonusSystemNode *nodeToMove = cai->whatShouldBeAttached();
-		nodeToMove->detachFrom(cai->whereShouldBeAttached(gs));
-		obj->setProperty(what,val);
-		nodeToMove->attachTo(cai->whereShouldBeAttached(gs));
+			gs->removeSightnObj(obj);
+			CBonusSystemNode *nodeToMove = cai->whatShouldBeAttached();
+			nodeToMove->detachFrom(cai->whereShouldBeAttached(gs));
+			obj->setProperty(what,val);
+			nodeToMove->attachTo(cai->whereShouldBeAttached(gs));
+			gs->addSightObj(obj);
+		}
+		else
+		{
+			gs->removeSightnObj(obj);
+			obj->setProperty(what, val);
+			gs->addSightObj(obj);
+		}
 	}
 	else //not an armed instance
 	{
diff --git a/server/CGameHandler.cpp b/server/CGameHandler.cpp
index d34639483..a9cc44df7 100644
--- a/server/CGameHandler.cpp
+++ b/server/CGameHandler.cpp
@@ -6291,21 +6291,6 @@ void CGameHandler::changeFogOfWar(int3 center, ui32 radius, PlayerColor player,
 {
 	std::unordered_set<int3, ShashInt3> tiles;
 	getTilesInRange(tiles, center, radius, player, hide? -1 : 1);
-	if (hide)
-	{
-		std::unordered_set<int3, ShashInt3> observedTiles; //do not hide tiles observed by heroes. May lead to disastrous AI problems
-		auto p = getPlayer(player);
-		for (auto h : p->heroes)
-		{
-			getTilesInRange(observedTiles, h->getSightCenter(), h->getSightRadius(), h->tempOwner, -1);
-		}
-		for (auto t : p->towns)
-		{
-			getTilesInRange(observedTiles, t->getSightCenter(), t->getSightRadius(), t->tempOwner, -1);
-		}
-		for (auto tile : observedTiles)
-			vstd::erase_if_present (tiles, tile);
-	}
 	changeFogOfWar(tiles, player, hide);
 }